| Abdra brachycarpa | Greene | Brassicaceae | 8 |
| Abronia ameliae | Lundell | Nyctaginaceae | 8 |
| Abronia angustifolia | Greene | Nyctaginaceae | 8 |
| Abronia carnea | Greene | Nyctaginaceae | 8 |
| Abronia fragrans | Nutt. ex Hook. | Nyctaginaceae | 8 |
| Abronia macrocarpa | L.A.Galloway | Nyctaginaceae | 8 |
| Abronia nealleyi | Standl. | Nyctaginaceae | 8 |
| Abutilon abutiloides | (Jacq.) Garcke ex Hochr. | Malvaceae | 8 |
| Abutilon fruticosum | Guill. & Perr. | Malvaceae | 8 |
| Abutilon hypoleucum | A.Gray | Malvaceae | 8 |
| Abutilon malacum | S.Watson | Malvaceae | 8 |
| Abutilon mollicomum | (Willd.) Sweet | Malvaceae | 8 |
| Abutilon parvulum | A.Gray | Malvaceae | 8 |
| Abutilon trisulcatum | Urb. | Malvaceae | 8 |
| Abutilon viscosum | (L.) Dorr | Malvaceae | 8 |
| Abutilon wrightii | A.Gray | Malvaceae | 8 |
| Acaciella angustissima | (Mill.) Britton & Rose | Fabaceae | 8 |
| Acalypha gracilens | A.Gray | Euphorbiaceae | 8 |
| Acalypha monococca | (Engelm. ex A.Gray) Lill.W.Mill. & Gandhi | Euphorbiaceae | 8 |
| Acalypha monostachya | Cav. | Euphorbiaceae | 8 |
| Acalypha neomexicana | Müll.Arg. | Euphorbiaceae | 8 |
| Acalypha persimilis | Müll.Arg. | Euphorbiaceae | 8 |
| Acalypha phleoides | Cav. | Euphorbiaceae | 8 |
| Acalypha poiretii | Spreng. | Euphorbiaceae | 8 |
| Acalypha radians | Torr. | Euphorbiaceae | 8 |
| Acalypha rhomboidea | Raf. | Euphorbiaceae | 8 |
| Acalypha virginica | L. | Euphorbiaceae | 8 |
| Acanthocereus tetragonus | (L.) Hummelinck | Cactaceae | 8 |
| Acer negundo | L. | Sapindaceae | 8 |
| Acer rubrum | L. | Sapindaceae | 8 |
| Acer saccharinum | L. | Sapindaceae | 8 |
| Acer saccharum | Marshall | Sapindaceae | 8 |
| Acleisanthes anisophylla | A.Gray | Nyctaginaceae | 8 |
| Acleisanthes chenopodioides | (A.Gray) R.A.Levin | Nyctaginaceae | 8 |
| Acleisanthes diffusa | (A.Gray) R.A.Levin | Nyctaginaceae | 8 |
| Acleisanthes lanceolata | (Wooton) R.A.Levin | Nyctaginaceae | 8 |
| Acleisanthes longiflora | A.Gray | Nyctaginaceae | 8 |
| Acleisanthes obtusa | (Choisy) Standl. | Nyctaginaceae | 8 |
| Acmella repens | Rich. ex Pers. | Asteraceae | 8 |
| Acmispon americanus | (Nutt.) Rydb. | Fabaceae | 8 |
| Acmispon brachycarpus | (Benth.) D.D.Sokoloff | Fabaceae | 8 |
| Acmispon oroboides | (Kunth) Brouillet | Fabaceae | 8 |
| Acourtia nana | (A.Gray) Reveal & R.M.King | Asteraceae | 8 |
| Acourtia runcinata | (D.Don) B.L.Turner | Asteraceae | 8 |
| Acourtia wrightii | (A.Gray) Reveal & R.M.King | Asteraceae | 8 |
| Adelia vaseyi | (J.M.Coult.) Pax & K.Hoffm. | Euphorbiaceae | 8 |
| Adiantum capillus-veneris | L. | Pteridaceae | 8 |
| Adiantum tricholepis | Fée | Pteridaceae | 8 |
| Adolphia infesta | (Kunth) Meisn. | Rhamnaceae | 8 |
| Aeschynomene indica | L. | Fabaceae | 8 |
| Aesculus glabra | Willd. | Sapindaceae | 8 |
| Aesculus pavia | L. | Sapindaceae | 8 |
| Agalinis densiflora | (Benth.) S.F.Blake | Orobanchaceae | 8 |
| Agalinis edwardsiana | Pennell | Orobanchaceae | 8 |
| Agalinis fasciculata | (Elliott) Raf. | Orobanchaceae | 8 |
| Agalinis gattingeri | (Small) Small ex Britton & A.Br. | Orobanchaceae | 8 |
| Agalinis harperi | Pennell | Orobanchaceae | 8 |
| Agalinis heterophylla | (Nutt.) Small ex Britton | Orobanchaceae | 8 |
| Agalinis homalantha | Pennell | Orobanchaceae | 8 |
| Agalinis maritima | (Raf.) Raf. | Orobanchaceae | 8 |
| Agalinis oligophylla | Pennell | Orobanchaceae | 8 |
| Agalinis purpurea | (L.) Pennell | Orobanchaceae | 8 |
| Agalinis strictifolia | (Benth.) Pennell | Orobanchaceae | 8 |
| Agalinis tenuifolia | (Vahl) Raf. | Orobanchaceae | 8 |
| Agalinis viridis | (Small) Pennell | Orobanchaceae | 8 |
| Agastache nepetoides | (L.) Kuntze | Lamiaceae | 8 |
| Agastache pallidiflora | (A.Heller) Rydb. | Lamiaceae | 8 |
| Agave americana | L. | Asparagaceae | 8 |
| Agave asperrima | Jacobi | Asparagaceae | 8 |
| Agave havardiana | Trel. | Asparagaceae | 8 |
| Agave lechuguilla | Torr. | Asparagaceae | 8 |
| Agave longiflora | (Rose) G.D.Rowley | Asparagaceae | 8 |
| Agave maculata | Regel | Asparagaceae | 8 |
| Agave parryi | Engelm. | Asparagaceae | 8 |
| Agave univittata | Haw. | Asparagaceae | 8 |
| Agave variegata | Jacobi | Asparagaceae | 8 |
| Agave virginica | L. | Asparagaceae | 8 |
| Ageratina altissima | (L.) R.M.King & H.Rob. | Asteraceae | 8 |
| Ageratina havanensis | (Kunth) R.M.King & H.Rob. | Asteraceae | 8 |
| Ageratina herbacea | (A.Gray) R.M.King & H.Rob. | Asteraceae | 8 |
| Ageratina rothrockii | (A.Gray) R.M.King & H.Rob. | Asteraceae | 8 |
| Ageratina wrightii | (A.Gray) R.M.King & H.Rob. | Asteraceae | 8 |
| Ageratum corymbosum | Zucc. ex Pers. | Asteraceae | 8 |
| Agrimonia microcarpa | Wallr. | Rosaceae | 8 |
| Agrimonia parviflora | Aiton | Rosaceae | 8 |
| Agrimonia pubescens | Wallr. | Rosaceae | 8 |
| Agrimonia rostellata | Wallr. | Rosaceae | 8 |
| Agrostis hyemalis | (Walter) Britton, Sterns & Poggenb. | Poaceae | 8 |
| Agrostis perennans | (Walter) Tuck. | Poaceae | 8 |
| Agrostis scabra | Willd. | Poaceae | 8 |
| Aldama cordifolia | (A.Gray) E.E.Schill. & Panero | Asteraceae | 8 |
| Aletris aurea | Walter | Nartheciaceae | 8 |
| Aletris farinosa | L. | Nartheciaceae | 8 |
| Alisma subcordatum | Raf. | Alismataceae | 8 |
| Allenrolfea occidentalis | (S.Watson) Kuntze | Chenopodiaceae | 8 |
| Allionia choisyi | Standl. | Nyctaginaceae | 8 |
| Allionia incarnata | L. | Nyctaginaceae | 8 |
| Allium canadense | L. | Amaryllidaceae | 8 |
| Allium cernuum | Roth | Amaryllidaceae | 8 |
| Allium coryi | M.E.Jones | Amaryllidaceae | 8 |
| Allium drummondii | Regel | Amaryllidaceae | 8 |
| Allium fraseri | (Ownbey) Shinners | Amaryllidaceae | 8 |
| Allium geyeri | S.Watson | Amaryllidaceae | 8 |
| Allium longifolium | (Kunth) Spreng. | Amaryllidaceae | 8 |
| Allium macropetalum | Rydb. | Amaryllidaceae | 8 |
| Allium rhizomatum | Wooton & Standl. | Amaryllidaceae | 8 |
| Allium runyonii | Ownbey | Amaryllidaceae | 8 |
| Allium stellatum | Nutt. ex Ker Gawl. | Amaryllidaceae | 8 |
| Allowissadula holosericea | (Scheele) D.M.Bates | Malvaceae | 8 |
| Alnus serrulata | (Aiton) Willd. | Betulaceae | 8 |
| Alopecurus carolinianus | Walter | Poaceae | 8 |
| Alophia drummondii | (Graham) R.C.Foster | Iridaceae | 8 |
| Aloysia gratissima | (Gillies & Hook.) Tronc. | Verbenaceae | 8 |
| Aloysia macrostachya | (Torr.) Moldenke | Verbenaceae | 8 |
| Aloysia wrightii | A.Heller | Verbenaceae | 8 |
| Amaranthus albus | L. | Amaranthaceae | 8 |
| Amaranthus blitoides | S.Watson | Amaranthaceae | 8 |
| Amaranthus fimbriatus | (Torr.) Benth. ex S.Watson | Amaranthaceae | 8 |
| Amaranthus greggii | S.Watson | Amaranthaceae | 8 |
| Amaranthus hybridus | L. | Amaranthaceae | 8 |
| Amaranthus hypochondriacus | L. | Amaranthaceae | 8 |
| Amaranthus palmeri | S.Watson | Amaranthaceae | 8 |
| Amaranthus polygonoides | L. | Amaranthaceae | 8 |
| Amaranthus powellii | S.Watson | Amaranthaceae | 8 |
| Amaranthus tuberculatus | (Moq.) J.D.Sauer | Amaranthaceae | 8 |
| Amaranthus watsonii | Standl. | Amaranthaceae | 8 |
| Amblyolepis setigera | DC. | Asteraceae | 8 |
| Ambrosia acanthicarpa | Hook. | Asteraceae | 8 |
| Ambrosia artemisiifolia | L. | Asteraceae | 8 |
| Ambrosia bidentata | Michx. | Asteraceae | 8 |
| Ambrosia cheiranthifolia | A.Gray | Asteraceae | 8 |
| Ambrosia confertiflora | DC. | Asteraceae | 8 |
| Ambrosia grayi | (A.Nelson) Shinners | Asteraceae | 8 |
| Ambrosia psilostachya | DC. | Asteraceae | 8 |
| Ambrosia trifida | L. | Asteraceae | 8 |
| Amelanchier alnifolia | (Nutt.) Nutt. ex M.Roem. | Rosaceae | 8 |
| Amelanchier arborea | (F.Michx.) Fernald | Rosaceae | 8 |
| Amelanchier utahensis | Koehne | Rosaceae | 8 |
| Ammannia auriculata | Willd. | Lythraceae | 8 |
| Ammannia coccinea | Rottb. | Lythraceae | 8 |
| Ammannia latifolia | L. | Lythraceae | 8 |
| Ammannia robusta | Heer & Regel | Lythraceae | 8 |
| Ammoselinum butleri | (Engelm. ex S.Watson) J.M.Coult. & Rose | Apiaceae | 8 |
| Ammoselinum popei | Torr. & A.Gray | Apiaceae | 8 |
| Amorpha canescens | Pursh | Fabaceae | 8 |
| Amorpha fruticosa | L. | Fabaceae | 8 |
| Amorpha paniculata | Torr. & A.Gray | Fabaceae | 8 |
| Amorpha roemeriana | Scheele | Fabaceae | 8 |
| Ampelopsis cordata | Michx. | Vitaceae | 8 |
| Amphiachyris amoena | (Shinners) Solbrig | Asteraceae | 8 |
| Amphicarpaea bracteata | (L.) Fernald | Fabaceae | 8 |
| Amsinckia menziesii | (Lehm.) A.Nelson & J.F.Macbr. | Boraginaceae | 8 |
| Amsinckia tessellata | A.Gray | Boraginaceae | 8 |
| Amsonia ciliata | Walter | Apocynaceae | 8 |
| Amsonia longiflora | Torr. | Apocynaceae | 8 |
| Amsonia palmeri | A.Gray | Apocynaceae | 8 |
| Amsonia tabernaemontana | Walter | Apocynaceae | 8 |
| Amsonia tomentosa | Torr. & Frém. | Apocynaceae | 8 |
| Amyris madrensis | S.Watson | Rutaceae | 8 |
| Amyris texana | P.Wilson | Rutaceae | 8 |
| Anaphalis margaritacea | (L.) Benth. & Hook.f. | Asteraceae | 8 |
| Anchistea virginica | (L.) C.Presl | Blechnaceae | 8 |
| Andersonglossum virginianum | (L.) J.I.Cohen | Boraginaceae | 8 |
| Andropogon cirratus | Hack. | Poaceae | 8 |
| Andropogon hallii | Hack. | Poaceae | 8 |
| Andropogon virginicus | L. | Poaceae | 8 |
| Androsace occidentalis | Pursh | Primulaceae | 8 |
| Androsace septentrionalis | L. | Primulaceae | 8 |
| Anemone berlandieri | Pritz. | Ranunculaceae | 8 |
| Anemone caroliniana | Walter | Ranunculaceae | 8 |
| Anemone edwardsiana | Tharp | Ranunculaceae | 8 |
| Anemone okennonii | Keener & B.E.Dutton | Ranunculaceae | 8 |
| Anemone tuberosa | Rydb. | Ranunculaceae | 8 |
| Anemopsis californica | (Nutt.) Hook. & Arn. | Saururaceae | 8 |
| Anisacanthus linearis | (S.H.Hagen) Henrickson & E.J.Lott | Acanthaceae | 8 |
| Anisacanthus quadrifidus | (Vahl) Nees | Acanthaceae | 8 |
| Anoda crenatiflora | Ortega | Malvaceae | 8 |
| Anoda cristata | (L.) Schltdl. | Malvaceae | 8 |
| Anoda lanceolata | Hook. & Arn. | Malvaceae | 8 |
| Anoda pentaschista | A.Gray | Malvaceae | 8 |
| Anredera vesicaria | (Lam.) C.F.Gaertn. | Basellaceae | 8 |
| Antennaria marginata | Greene | Asteraceae | 8 |
| Antennaria parlinii | Fernald | Asteraceae | 8 |
| Antennaria parvifolia | Nutt. | Asteraceae | 8 |
| Anthenantia villosa | (Michx.) P.Beauv. | Poaceae | 8 |
| Anticlea elegans | (Pursh) Rydb. | Melanthiaceae | 8 |
| Aphanostephus ramosissimus | DC. | Asteraceae | 8 |
| Apios americana | Medik. | Fabaceae | 8 |
| Apocynum androsaemifolium | L. | Apocynaceae | 8 |
| Apocynum cannabinum | L. | Apocynaceae | 8 |
| Apodanthera undulata | A.Gray | Cucurbitaceae | 8 |
| Apteria aphylla | (Nutt.) Barnhart ex Small | Burmanniaceae | 8 |
| Aquarius cordifolius | (L.) Christenh. & Byng | Alismataceae | 8 |
| Aquilegia canadensis | L. | Ranunculaceae | 8 |
| Aquilegia chrysantha | A.Gray | Ranunculaceae | 8 |
| Aquilegia longissima | A.Gray ex S.Watson | Ranunculaceae | 8 |
| Aralia bicrenata | Wooton & Standl. | Araliaceae | 8 |
| Aralia spinosa | L. | Araliaceae | 8 |
| Arbutus xalapensis | Kunth | Ericaceae | 8 |
| Arceuthobium divaricatum | Engelm. | Santalaceae | 8 |
| Arceuthobium douglasii | Engelm. | Santalaceae | 8 |
| Arceuthobium vaginatum | (Humb. & Bonpl. ex Willd.) J.Presl | Santalaceae | 8 |
| Arctostaphylos pungens | Kunth | Ericaceae | 8 |
| Arenaria benthamii | Fenzl ex Torr. & A.Gray | Caryophyllaceae | 8 |
| Arenaria lanuginosa | (Michx.) Rohrb. | Caryophyllaceae | 8 |
| Argemone aenea | Ownbey | Papaveraceae | 8 |
| Argemone albiflora | Hornem. | Papaveraceae | 8 |
| Argemone aurantiaca | Ownbey | Papaveraceae | 8 |
| Argemone polyanthemos | (Fedde) Ownbey | Papaveraceae | 8 |
| Argemone sanguinea | Greene | Papaveraceae | 8 |
| Argemone squarrosa | Greene | Papaveraceae | 8 |
| Argyrochosma dealbata | (Pursh) Windham | Pteridaceae | 8 |
| Argyrochosma limitanea | (Maxon) Windham | Pteridaceae | 8 |
| Argyrochosma microphylla | (Kuhn) Windham | Pteridaceae | 8 |
| Arisaema dracontium | (L.) Schott | Araceae | 8 |
| Arisaema pusillum | (Peck) Nash | Araceae | 8 |
| Arisaema quinatum | (Nutt.) Schott | Araceae | 8 |
| Arisaema triphyllum | (L.) Schott | Araceae | 8 |
| Aristida adscensionis | L. | Poaceae | 8 |
| Aristida arizonica | Vasey | Poaceae | 8 |
| Aristida desmantha | Trin. & Rupr. | Poaceae | 8 |
| Aristida divaricata | Humb. & Bonpl. ex Willd. | Poaceae | 8 |
| Aristida lanosa | Muhl. ex Elliott | Poaceae | 8 |
| Aristida longespica | Poir. | Poaceae | 8 |
| Aristida oligantha | Michx. | Poaceae | 8 |
| Aristida palustris | (Chapm.) Vasey | Poaceae | 8 |
| Aristida pansa | Wooton & Standl. | Poaceae | 8 |
| Aristida purpurascens | Poir. | Poaceae | 8 |
| Aristida purpurea | Nutt. | Poaceae | 8 |
| Aristida spiciformis | Elliott | Poaceae | 8 |
| Aristida ternipes | Cav. | Poaceae | 8 |
| Aristida virgata | Trin. | Poaceae | 8 |
| Aristolochia coryi | I.M.Johnst. | Aristolochiaceae | 8 |
| Aristolochia erecta | L. | Aristolochiaceae | 8 |
| Aristolochia pentandra | Jacq. | Aristolochiaceae | 8 |
| Aristolochia serpentaria | L. | Aristolochiaceae | 8 |
| Aristolochia tomentosa | Sims | Aristolochiaceae | 8 |
| Aristolochia wrightii | Seem. | Aristolochiaceae | 8 |
| Arnoglossum ovatum | (Walter) H.Rob. | Asteraceae | 8 |
| Arnoglossum plantagineum | Raf. | Asteraceae | 8 |
| Aronia arbutifolia | (L.) Pers. | Rosaceae | 8 |
| Artemisia bigelovii | A.Gray | Asteraceae | 8 |
| Artemisia campestris | L. | Asteraceae | 8 |
| Artemisia carruthii | Alph.Wood ex J.H.Carruth | Asteraceae | 8 |
| Artemisia dracunculus | L. | Asteraceae | 8 |
| Artemisia filifolia | Torr. | Asteraceae | 8 |
| Artemisia frigida | Willd. | Asteraceae | 8 |
| Artemisia ludoviciana | Nutt. | Asteraceae | 8 |
| Arundinaria gigantea | (Walter) Muhl. | Poaceae | 8 |
| Asarum arifolium | Michx. | Aristolochiaceae | 8 |
| Asclepias amplexicaulis | Sm. | Apocynaceae | 8 |
| Asclepias arenaria | Torr. | Apocynaceae | 8 |
| Asclepias asperula | (Decne.) Woodson | Apocynaceae | 8 |
| Asclepias brachystephana | Engelm. ex Torr. | Apocynaceae | 8 |
| Asclepias emoryi | (Greene) Vail | Apocynaceae | 8 |
| Asclepias engelmanniana | Woodson | Apocynaceae | 8 |
| Asclepias hirtella | (Pennell) Woodson | Apocynaceae | 8 |
| Asclepias incarnata | L. | Apocynaceae | 8 |
| Asclepias involucrata | Engelm. ex Torr. | Apocynaceae | 8 |
| Asclepias lanceolata | Walter | Apocynaceae | 8 |
| Asclepias latifolia | (Torr.) Raf. | Apocynaceae | 8 |
| Asclepias linearis | Scheele | Apocynaceae | 8 |
| Asclepias nummularia | Torr. | Apocynaceae | 8 |
| Asclepias obovata | Elliott | Apocynaceae | 8 |
| Asclepias oenotheroides | Schltdl. & Cham. | Apocynaceae | 8 |
| Asclepias perennis | Walter | Apocynaceae | 8 |
| Asclepias prostrata | W.H.Blackw. | Apocynaceae | 8 |
| Asclepias pumila | (A.Gray) Vail | Apocynaceae | 8 |
| Asclepias purpurascens | L. | Apocynaceae | 8 |
| Asclepias rubra | L. | Apocynaceae | 8 |
| Asclepias speciosa | Torr. | Apocynaceae | 8 |
| Asclepias stenophylla | A.Gray | Apocynaceae | 8 |
| Asclepias subverticillata | (A.Gray) Vail | Apocynaceae | 8 |
| Asclepias texana | A.Heller | Apocynaceae | 8 |
| Asclepias tonkawae | D.P.Duran, J.Ksepka, S.A.Davis, Godwin & R.A.S.Laroche | Apocynaceae | 8 |
| Asclepias tuberosa | L. | Apocynaceae | 8 |
| Asclepias variegata | L. | Apocynaceae | 8 |
| Asclepias verticillata | L. | Apocynaceae | 8 |
| Asclepias viridiflora | Raf. | Apocynaceae | 8 |
| Asclepias viridis | Walter | Apocynaceae | 8 |
| Asimina parviflora | (Michx.) Dunal | Annonaceae | 8 |
| Asimina triloba | (L.) Dunal | Annonaceae | 8 |
| Aspicarpa hirtella | Rich. | Malpighiaceae | 8 |
| Aspicarpa hyssopifolia | A.Gray | Malpighiaceae | 8 |
| Asplenium platyneuron | (L.) Britton, Sterns & Poggenb. | Aspleniaceae | 8 |
| Asplenium resiliens | Kunze | Aspleniaceae | 8 |
| Asplenium septentrionale | (L.) Hoffm. | Aspleniaceae | 8 |
| Asplenium trichomanes | L. | Aspleniaceae | 8 |
| Aster subulatus | Michx. | Asteraceae | 8 |
| Astragalus allochrous | A.Gray | Fabaceae | 8 |
| Astragalus amphioxys | A.Gray | Fabaceae | 8 |
| Astragalus canadensis | L. | Fabaceae | 8 |
| Astragalus crassicarpus | Nutt. | Fabaceae | 8 |
| Astragalus distortus | Torr. & A.Gray | Fabaceae | 8 |
| Astragalus emoryanus | (Rydb.) Cory | Fabaceae | 8 |
| Astragalus gracilis | Nutt. | Fabaceae | 8 |
| Astragalus gypsodes | Barneby | Fabaceae | 8 |
| Astragalus humistratus | A.Gray | Fabaceae | 8 |
| Astragalus lentiginosus | Douglas ex Hook. | Fabaceae | 8 |
| Astragalus leptocarpus | Torr. & A.Gray | Fabaceae | 8 |
| Astragalus lindheimeri | Engelm. ex A.Gray | Fabaceae | 8 |
| Astragalus lotiflorus | Hook. | Fabaceae | 8 |
| Astragalus missouriensis | Nutt. | Fabaceae | 8 |
| Astragalus mollissimus | Torr. | Fabaceae | 8 |
| Astragalus nuttallianus | DC. | Fabaceae | 8 |
| Astragalus plattensis | Nutt. | Fabaceae | 8 |
| Astragalus praelongus | E.Sheld. | Fabaceae | 8 |
| Astragalus racemosus | Pursh | Fabaceae | 8 |
| Astragalus reflexus | Torr. & A.Gray | Fabaceae | 8 |
| Astragalus wootonii | E.Sheld. | Fabaceae | 8 |
| Astragalus wrightii | A.Gray | Fabaceae | 8 |
| Astranthium ciliatum | (Raf.) G.L.Nesom | Asteraceae | 8 |
| Astrolepis cochisensis | (Goodd.) D.M.Benham & Windham | Pteridaceae | 8 |
| Astrolepis integerrima | (Hook.) D.M.Benham & Windham | Pteridaceae | 8 |
| Astrolepis sinuata | (Lag. ex Sw.) D.M.Benham & Windham | Pteridaceae | 8 |
| Astrolepis windhamii | D.M.Benham | Pteridaceae | 8 |
| Astrophytum asterias | (Zucc.) Lem. | Cactaceae | 8 |
| Athyrium asplenioides | (Michx.) Desv. | Athyriaceae | 8 |
| Atriplex acanthocarpa | (Torr.) S.Watson | Chenopodiaceae | 8 |
| Atriplex argentea | Nutt. | Chenopodiaceae | 8 |
| Atriplex canescens | (Pursh) Nutt. | Chenopodiaceae | 8 |
| Atriplex confertifolia | (Torr. & Frém.) S.Watson | Chenopodiaceae | 8 |
| Atriplex elegans | (Moq.) D.Dietr. | Chenopodiaceae | 8 |
| Atriplex lentiformis | (Torr.) S.Watson | Chenopodiaceae | 8 |
| Atriplex obovata | Moq. | Chenopodiaceae | 8 |
| Atriplex saccaria | S.Watson | Chenopodiaceae | 8 |
| Aureolaria flava | (L.) Farw. | Orobanchaceae | 8 |
| Aureolaria grandiflora | (Benth.) Pennell | Orobanchaceae | 8 |
| Aureolaria pectinata | (Nutt.) Pennell | Orobanchaceae | 8 |
| Aureolaria virginica | (L.) Pennell | Orobanchaceae | 8 |
| Avenella flexuosa | (L.) Drejer | Poaceae | 8 |
| Avicennia germinans | (L.) L. | Acanthaceae | 8 |
| Axonopus compressus | (Sw.) P.Beauv. | Poaceae | 8 |
| Axonopus fissifolius | (Raddi) Kuhlm. | Poaceae | 8 |
| Axonopus furcatus | (Flüggé) Hitchc. | Poaceae | 8 |
| Ayenia filiformis | S.Watson | Malvaceae | 8 |
| Ayenia limitaris | Cristóbal | Malvaceae | 8 |
| Ayenia microphylla | A.Gray | Malvaceae | 8 |
| Azolla caroliniana | Willd. | Salviniaceae | 8 |
| Azolla filiculoides | Lam. | Salviniaceae | 8 |
| Baccharis brachyphylla | A.Gray | Asteraceae | 8 |
| Baccharis halimifolia | L. | Asteraceae | 8 |
| Baccharis neglecta | Britton | Asteraceae | 8 |
| Baccharis pteronioides | DC. | Asteraceae | 8 |
| Baccharis salicifolia | (Ruiz & Pav.) Pers. | Asteraceae | 8 |
| Baccharis salicina | Torr. & A.Gray | Asteraceae | 8 |
| Baccharis sarothroides | A.Gray | Asteraceae | 8 |
| Baccharis texana | A.Gray | Asteraceae | 8 |
| Baccharis wrightii | A.Gray | Asteraceae | 8 |
| Bacopa caroliniana | (Walter) B.L.Rob. | Plantaginaceae | 8 |
| Bacopa monnieri | (L.) Wettst. | Plantaginaceae | 8 |
| Baptisia australis | (L.) R.Br. | Fabaceae | 8 |
| Baptisia lactea | (Raf.) Thieret | Fabaceae | 8 |
| Baptisia leucophaea | Nutt. | Fabaceae | 8 |
| Baptisia nuttalliana | Small | Fabaceae | 8 |
| Baptisia sphaerocarpa | Nutt. | Fabaceae | 8 |
| Barkleyanthus salicifolius | (Kunth) H.Rob. & Brettell | Asteraceae | 8 |
| Bartlettia scaposa | A.Gray | Asteraceae | 8 |
| Bartonia paniculata | (Michx.) Muhl. | Gentianaceae | 8 |
| Bartonia verna | (Michx.) Raf. ex Barton | Gentianaceae | 8 |
| Bartonia virginica | (L.) Britton, Sterns & Poggenb. | Gentianaceae | 8 |
| Batis maritima | L. | Bataceae | 8 |
| Bauhinia lunarioides | A.Gray ex S.Watson | Fabaceae | 8 |
| Bebbia juncea | Greene | Asteraceae | 8 |
| Berberis haematocarpa | Wooton | Berberidaceae | 8 |
| Berberis repens | Lindl. | Berberidaceae | 8 |
| Berberis swaseyi | Buckley | Berberidaceae | 8 |
| Berberis trifoliolata | Moric. | Berberidaceae | 8 |
| Berchemia scandens | (Hill) K.Koch | Rhamnaceae | 8 |
| Berlandiera betonicifolia | Small | Asteraceae | 8 |
| Berlandiera lyrata | Benth. | Asteraceae | 8 |
| Berlandiera pumila | (Michx.) Nutt. | Asteraceae | 8 |
| Berlandiera texana | DC. | Asteraceae | 8 |
| Bernardia myricifolia | (Scheele) S.Watson | Euphorbiaceae | 8 |
| Bernardia obovata | I.M.Johnst. | Euphorbiaceae | 8 |
| Berula erecta | (Huds.) Coville | Apiaceae | 8 |
| Betula nigra | L. | Betulaceae | 8 |
| Bidens alba | DC. | Asteraceae | 8 |
| Bidens aristosa | Britton | Asteraceae | 8 |
| Bidens bigelovii | A.Gray | Asteraceae | 8 |
| Bidens bipinnata | L. | Asteraceae | 8 |
| Bidens cernua | L. | Asteraceae | 8 |
| Bidens discoidea | Britton | Asteraceae | 8 |
| Bidens frondosa | L. | Asteraceae | 8 |
| Bidens laevis | (L.) Britton, Sterns & Poggenb. | Asteraceae | 8 |
| Bidens leptocephala | Sherff | Asteraceae | 8 |
| Bidens mitis | Sherff | Asteraceae | 8 |
| Bidens pilosa | L. | Asteraceae | 8 |
| Bidens polylepis | S.F.Blake | Asteraceae | 8 |
| Bidens tripartita | L. | Asteraceae | 8 |
| Bifora americana | Benth. & Hook.f. ex S.Watson | Apiaceae | 8 |
| Bigelowia nudata | (Michx.) DC. | Asteraceae | 8 |
| Bigelowia nuttallii | L.C.Anderson | Asteraceae | 8 |
| Bignonia capreolata | L. | Bignoniaceae | 8 |
| Billieturnera helleri | (Rose ex Heller) Fryxell | Malvaceae | 8 |
| Blechnum appendiculatum | Willd. | Blechnaceae | 8 |
| Blephilia hirsuta | (Pursh) Benth. | Lamiaceae | 8 |
| Bletia arizonica | (S.Watson) Sosa & M.W.Chase | Orchidaceae | 8 |
| Bletia mexicana | (Greenm.) Sosa & M.W.Chase | Orchidaceae | 8 |
| Bletia nitida | (L.O.Williams) Sosa & M.W.Chase | Orchidaceae | 8 |
| Bletia spicata | (Walter) Sosa & M.W.Chase | Orchidaceae | 8 |
| Bletia warnockii | (Ames & Correll) Sosa & M.W.Chase | Orchidaceae | 8 |
| Blitum nuttallianum | Schult. | Chenopodiaceae | 8 |
| Boechera perennans | (S.Watson) W.A.Weber | Brassicaceae | 8 |
| Boehmeria cylindrica | (L.) Sw. | Urticaceae | 8 |
| Boerhavia coccinea | Mill. | Nyctaginaceae | 8 |
| Boerhavia coulteri | (Hook.f.) S.Watson | Nyctaginaceae | 8 |
| Boerhavia erecta | L. | Nyctaginaceae | 8 |
| Boerhavia gracillima | Heimerl | Nyctaginaceae | 8 |
| Boerhavia linearifolia | A.Gray | Nyctaginaceae | 8 |
| Boerhavia purpurascens | A.Gray | Nyctaginaceae | 8 |
| Boerhavia scandens | L. | Nyctaginaceae | 8 |
| Boerhavia triquetra | S.Watson | Nyctaginaceae | 8 |
| Boerhavia wrightii | A.Gray | Nyctaginaceae | 8 |
| Bolboschoenus maritimus | (L.) Palla | Cyperaceae | 8 |
| Bolboschoenus robustus | (Pursh) Soják | Cyperaceae | 8 |
| Boltonia asteroides | L'Hér. | Asteraceae | 8 |
| Boltonia diffusa | Elliott | Asteraceae | 8 |
| Bommeria hispida | Underw. | Pteridaceae | 8 |
| Bonamia ovalifolia | (Torr.) Hallier f. | Convolvulaceae | 8 |
| Borodinia canadensis | (L.) P.J.Alexander & Windham | Brassicaceae | 8 |
| Borrichia frutescens | (L.) DC. | Asteraceae | 8 |
| Bothriochloa barbinodis | (Lag.) Herter | Poaceae | 8 |
| Bothriochloa hybrida | (Gould) Gould | Poaceae | 8 |
| Bothriochloa longipaniculata | (Gould) Allred & Gould | Poaceae | 8 |
| Bothriochloa torreyana | (Steud.) Scrivanti & Anton | Poaceae | 8 |
| Botrypus virginianus | (L.) Michx. | Ophioglossaceae | 8 |
| Bouchea linifolia | A.Gray ex Torr. | Verbenaceae | 8 |
| Bouchetia erecta | Dunal | Solanaceae | 8 |
| Bouteloua aristidoides | (Kunth) Griseb. | Poaceae | 8 |
| Bouteloua barbata | Lag. | Poaceae | 8 |
| Bouteloua chondrosioides | (Kunth) Benth. ex S.Watson | Poaceae | 8 |
| Bouteloua curtipendula | (Michx.) Torr. | Poaceae | 8 |
| Bouteloua dactyloides | (Nutt.) Columbus | Poaceae | 8 |
| Bouteloua eriopoda | (Torr.) Torr. | Poaceae | 8 |
| Bouteloua gracilis | (Kunth) Lag. ex Griffiths | Poaceae | 8 |
| Bouteloua hirsuta | Lag. | Poaceae | 8 |
| Bouteloua parryi | (E.Fourn.) Griffiths | Poaceae | 8 |
| Bouteloua pectinata | Feath. | Poaceae | 8 |
| Bouteloua repens | (Kunth) Scribn. & Merr. | Poaceae | 8 |
| Bouteloua rigidiseta | (Steud.) Hitchc. | Poaceae | 8 |
| Bouteloua trifida | Thurb. ex S.Watson | Poaceae | 8 |
| Bouteloua uniflora | Vasey | Poaceae | 8 |
| Bouteloua warnockii | Gould & Kapadia | Poaceae | 8 |
| Bouvardia ternifolia | (Cav.) Schltdl. | Rubiaceae | 8 |
| Bowlesia incana | Ruiz & Pav. | Apiaceae | 8 |
| Brachyelytrum erectum | (Schreb.) P.Beauv. | Poaceae | 8 |
| Bradburia pilosa | (Nutt.) Semple | Asteraceae | 8 |
| Brasenia schreberi | J.F.Gmel. | Cabombaceae | 8 |
| Brazoria truncata | (Benth.) Engelm. & A.Gray | Lamiaceae | 8 |
| Brickellia baccharidea | A.Gray | Asteraceae | 8 |
| Brickellia coulteri | A.Gray | Asteraceae | 8 |
| Brickellia cylindracea | A.Gray & Engelm. | Asteraceae | 8 |
| Brickellia dentata | (DC.) Sch.Bip. | Asteraceae | 8 |
| Brickellia eupatorioides | (L.) Shinners | Asteraceae | 8 |
| Brickellia grandiflora | Nutt. | Asteraceae | 8 |
| Brickellia laciniata | A.Gray | Asteraceae | 8 |
| Brickellia leptophylla | (Scheele) Shinn. | Asteraceae | 8 |
| Brickellia veronicaefolia | (Kunth) A.Gray | Asteraceae | 8 |
| Brickelliastrum fendleri | (A.Gray) R.M.King & H.Rob. | Asteraceae | 8 |
| Bromus anomalus | Rupr. ex E.Fourn. | Poaceae | 8 |
| Bromus carinatus | Hook. & Arn. | Poaceae | 8 |
| Bromus ciliatus | L. | Poaceae | 8 |
| Bromus nottowayanus | Fernald | Poaceae | 8 |
| Bromus porteri | (Coult.) Nash | Poaceae | 8 |
| Bromus pubescens | Muhl. ex Willd. | Poaceae | 8 |
| Bromus texensis | (Shear) Hitchc. | Poaceae | 8 |
| Brunnichia ovata | (Walter) Shinners | Polygonaceae | 8 |
| Buchnera americana | L. | Orobanchaceae | 8 |
| Buchnera floridana | Gand. | Orobanchaceae | 8 |
| Buddleja marrubiifolia | Benth. | Scrophulariaceae | 8 |
| Buddleja racemosa | Torr. | Scrophulariaceae | 8 |
| Buddleja scordioides | Kunth | Scrophulariaceae | 8 |
| Buddleja sessiliflora | Kunth | Scrophulariaceae | 8 |
| Bulbostylis capillaris | (L.) Kunth ex C.B.Clarke | Cyperaceae | 8 |
| Bulbostylis ciliatifolia | (Elliott) Fernald | Cyperaceae | 8 |
| Burmannia biflora | L. | Burmanniaceae | 8 |
| Burmannia capitata | (Walter ex J.F.Gmel.) Mart. | Burmanniaceae | 8 |
| Cabomba caroliniana | A.Gray | Cabombaceae | 8 |
| Cakile constricta | Rodman | Brassicaceae | 8 |
| Calliandra eriophylla | Benth. | Fabaceae | 8 |
| Calliandra humilis | Benth. | Fabaceae | 8 |
| Callicarpa americana | L. | Lamiaceae | 8 |
| Callirhoe alcaeoides | (Michx.) A.Gray | Malvaceae | 8 |
| Callirhoe involucrata | (Torr. & A.Gray) A.Gray | Malvaceae | 8 |
| Callirhoe leiocarpa | R.F.Martin | Malvaceae | 8 |
| Callirhoe papaver | (Cav.) A.Gray | Malvaceae | 8 |
| Callirhoe pedata | (Nutt. ex Hook.) A.Gray | Malvaceae | 8 |
| Callisia micrantha | (Torr.) D.R.Hunt | Commelinaceae | 8 |
| Callisia repens | (Jacq.) L. | Commelinaceae | 8 |
| Callitriche heterophylla | Pursh | Plantaginaceae | 8 |
| Callitriche palustris | L. | Plantaginaceae | 8 |
| Callitriche terrestris | Raf. | Plantaginaceae | 8 |
| Calochortus kennedyi | Porter | Liliaceae | 8 |
| Calopogon oklahomensis | D.H.Goldman | Orchidaceae | 8 |
| Calopogon tuberosus | (L.) Britton, Sterns & Poggenb. | Orchidaceae | 8 |
| Calycoseris wrightii | A.Gray | Asteraceae | 8 |
| Calyptocarpus vialis | Less. | Asteraceae | 8 |
| Calystegia sepium | (L.) R.Br. | Convolvulaceae | 8 |
| Calystegia silvatica | Griseb. | Convolvulaceae | 8 |
| Camassia angusta | (Engelm. & A.Gray) Blank. | Asparagaceae | 8 |
| Camassia scilloides | (Raf.) Cory | Asparagaceae | 8 |
| Campanula petiolata | A.DC. | Campanulaceae | 8 |
| Campsis radicans | (L.) Bureau | Bignoniaceae | 8 |
| Canavalia rosea | (Sw.) DC. | Fabaceae | 8 |
| Canna flaccida | Salisb. | Cannaceae | 8 |
| Canna glauca | L. | Cannaceae | 8 |
| Canna indica | L. | Cannaceae | 8 |
| Capsicum annuum | L. | Solanaceae | 8 |
| Cardamine bulbosa | (Schreb. ex Muhl.) Britton, Sterns & Poggenb. | Brassicaceae | 8 |
| Cardamine concatenata | (Michx.) O.Schwarz | Brassicaceae | 8 |
| Cardamine parviflora | L. | Brassicaceae | 8 |
| Cardamine pensylvanica | Muhl. ex Willd. | Brassicaceae | 8 |
| Carex abscondita | Mack. | Cyperaceae | 8 |
| Carex albicans | Willd. ex Spreng. | Cyperaceae | 8 |
| Carex albolutescens | Schwein. | Cyperaceae | 8 |
| Carex amphibola | Steud. | Cyperaceae | 8 |
| Carex athrostachya | Olney | Cyperaceae | 8 |
| Carex atlantica | L.H.Bailey | Cyperaceae | 8 |
| Carex aurea | Nutt. | Cyperaceae | 8 |
| Carex aureolensis | Steud. | Cyperaceae | 8 |
| Carex austrina | Mack. | Cyperaceae | 8 |
| Carex basiantha | Steud. | Cyperaceae | 8 |
| Carex blanda | Dewey | Cyperaceae | 8 |
| Carex brevior | (Dewey) Mack. ex Lunell | Cyperaceae | 8 |
| Carex bromoides | Willd. | Cyperaceae | 8 |
| Carex bulbostylis | Mack. | Cyperaceae | 8 |
| Carex bushii | Mack. | Cyperaceae | 8 |
| Carex caroliniana | Schwein. | Cyperaceae | 8 |
| Carex cephalophora | Muhl. ex Willd. | Cyperaceae | 8 |
| Carex cherokeensis | Schwein. | Cyperaceae | 8 |
| Carex comosa | Boott | Cyperaceae | 8 |
| Carex complanata | Torr. & Hook. | Cyperaceae | 8 |
| Carex corrugata | Fernald | Cyperaceae | 8 |
| Carex crebriflora | Wiegand | Cyperaceae | 8 |
| Carex crinita | Lam. | Cyperaceae | 8 |
| Carex crus-corvi | Shuttlew. ex Kunze | Cyperaceae | 8 |
| Carex davisii | Schwein. & Torr. | Cyperaceae | 8 |
| Carex debilis | Michx. | Cyperaceae | 8 |
| Carex decomposita | Muhl. | Cyperaceae | 8 |
| Carex digitalis | Willd. | Cyperaceae | 8 |
| Carex eburnea | Boott | Cyperaceae | 8 |
| Carex emoryi | Dewey | Cyperaceae | 8 |
| Carex festucacea | Willd. | Cyperaceae | 8 |
| Carex flaccosperma | Dewey | Cyperaceae | 8 |
| Carex gigantea | Rudge | Cyperaceae | 8 |
| Carex glaucescens | Elliott | Cyperaceae | 8 |
| Carex glaucodea | Tuck. ex Olney | Cyperaceae | 8 |
| Carex granularis | Muhl. ex Willd. | Cyperaceae | 8 |
| Carex gravida | L.H.Bailey | Cyperaceae | 8 |
| Carex grisea | Wahlenb. | Cyperaceae | 8 |
| Carex hirsutella | Mack. | Cyperaceae | 8 |
| Carex hyalinolepis | Steud. | Cyperaceae | 8 |
| Carex hystericina | Muhl. ex Willd. | Cyperaceae | 8 |
| Carex ignota | Dewey | Cyperaceae | 8 |
| Carex intumescens | Rudge | Cyperaceae | 8 |
| Carex jamesii | Schwein. | Cyperaceae | 8 |
| Carex joorii | L.H.Bailey | Cyperaceae | 8 |
| Carex kraliana | Naczi & Bryson | Cyperaceae | 8 |
| Carex laxiflora | Lam. | Cyperaceae | 8 |
| Carex leavenworthii | Dewey | Cyperaceae | 8 |
| Carex leptalea | Wahlenb. | Cyperaceae | 8 |
| Carex lonchocarpa | Willd. ex Spreng. | Cyperaceae | 8 |
| Carex longii | Mack. | Cyperaceae | 8 |
| Carex louisianica | L.H.Bailey | Cyperaceae | 8 |
| Carex lupulina | Muhl. ex Willd. | Cyperaceae | 8 |
| Carex lurida | Wahlenb. | Cyperaceae | 8 |
| Carex meadii | Dewey | Cyperaceae | 8 |
| Carex microdonta | Torr. | Cyperaceae | 8 |
| Carex muehlenbergii | Schkuhr ex Willd. | Cyperaceae | 8 |
| Carex nigromarginata | Schwein. | Cyperaceae | 8 |
| Carex occidentalis | L.H.Bailey | Cyperaceae | 8 |
| Carex oxylepis | Torr. & Hook. | Cyperaceae | 8 |
| Carex pellita | Muhl. ex Willd. | Cyperaceae | 8 |
| Carex planispicata | Naczi | Cyperaceae | 8 |
| Carex planostachys | Kunze | Cyperaceae | 8 |
| Carex polystachya | Sw. ex Wahlenb. | Cyperaceae | 8 |
| Carex retroflexa | Muhl. ex Willd. | Cyperaceae | 8 |
| Carex rosea | Willd. | Cyperaceae | 8 |
| Carex stipata | Muhl. ex Willd. | Cyperaceae | 8 |
| Carex stricta | Lam. | Cyperaceae | 8 |
| Carex styloflexa | Buckley | Cyperaceae | 8 |
| Carex tenax | Chapm. ex Dewey | Cyperaceae | 8 |
| Carex tetrastachya | Scheele | Cyperaceae | 8 |
| Carex texensis | (Torr. ex L.H.Bailey) L.H.Bailey | Cyperaceae | 8 |
| Carex tribuloides | Wahlenb. | Cyperaceae | 8 |
| Carex typhina | Michx. | Cyperaceae | 8 |
| Carex vallicola | Dewey | Cyperaceae | 8 |
| Carex verrucosa | Muhl. | Cyperaceae | 8 |
| Carex vulpinoidea | Michx. | Cyperaceae | 8 |
| Carex willdenowii | Willd. | Cyperaceae | 8 |
| Carlowrightia arizonica | A.Gray | Acanthaceae | 8 |
| Carlowrightia linearifolia | (Torr.) A.Gray | Acanthaceae | 8 |
| Carlowrightia parviflora | (Buckley) Wassh. | Acanthaceae | 8 |
| Carlowrightia texana | Henrickson & T.F.Daniel | Acanthaceae | 8 |
| Carlowrightia torreyana | Wassh. | Acanthaceae | 8 |
| Carminatia tenuiflora | DC. | Asteraceae | 8 |
| Carphochaete bigelovii | A.Gray | Asteraceae | 8 |
| Carpinus caroliniana | Walter | Betulaceae | 8 |
| Carya aquatica | (F.Michx.) Nutt. ex Elliott | Juglandaceae | 8 |
| Carya cordiformis | (Wangenh.) K.Koch | Juglandaceae | 8 |
| Carya glabra | (Mill.) Sweet | Juglandaceae | 8 |
| Carya illinoinensis | (Wangenh.) K.Koch | Juglandaceae | 8 |
| Carya laciniosa | (F.Michx.) G.Don | Juglandaceae | 8 |
| Carya myristiciformis | (F.Michx.) Nutt. ex Elliott | Juglandaceae | 8 |
| Carya ovata | (Mill.) K.Koch | Juglandaceae | 8 |
| Carya texana | Buckley | Juglandaceae | 8 |
| Carya tomentosa | (Lam.) Nutt. | Juglandaceae | 8 |
| Castanea ozarkensis | Ashe | Fagaceae | 8 |
| Castanea pumila | (L.) Mill. | Fagaceae | 8 |
| Castela tortuosa | Liebm. | Simaroubaceae | 8 |
| Castilleja citrina | Pennell | Orobanchaceae | 8 |
| Castilleja coccinea | (L.) Spreng. | Orobanchaceae | 8 |
| Castilleja genevievana | G.L.Nesom | Orobanchaceae | 8 |
| Castilleja indivisa | Engelm. | Orobanchaceae | 8 |
| Castilleja integra | A.Gray | Orobanchaceae | 8 |
| Castilleja lanata | A.Gray | Orobanchaceae | 8 |
| Castilleja lindheimeri | A.Gray | Orobanchaceae | 8 |
| Castilleja mexicana | (Hemsl.) A.Gray | Orobanchaceae | 8 |
| Castilleja purpurea | (Nutt.) G.Don | Orobanchaceae | 8 |
| Castilleja sessiliflora | Pursh | Orobanchaceae | 8 |
| Castilleja wootonii | Standl. | Orobanchaceae | 8 |
| Catalpa bignonioides | Walter | Bignoniaceae | 8 |
| Catalpa speciosa | (Warder) Engelm. | Bignoniaceae | 8 |
| Cayaponia quinqueloba | (Raf.) Shinners | Cucurbitaceae | 8 |
| Ceanothus americanus | L. | Rhamnaceae | 8 |
| Ceanothus fendleri | A.Gray | Rhamnaceae | 8 |
| Ceanothus herbaceus | Raf. | Rhamnaceae | 8 |
| Ceanothus pauciflorus | DC. | Rhamnaceae | 8 |
| Celastrus scandens | L. | Celastraceae | 8 |
| Celosia nitida | Vahl | Amaranthaceae | 8 |
| Celtis laevigata | Willd. | Cannabaceae | 8 |
| Celtis occidentalis | L. | Cannabaceae | 8 |
| Celtis pallida | Torr. | Cannabaceae | 8 |
| Celtis reticulata | Torr. | Cannabaceae | 8 |
| Celtis tenuifolia | Nutt. | Cannabaceae | 8 |
| Cenchrus echinatus | L. | Poaceae | 8 |
| Cenchrus myosuroides | Kunth | Poaceae | 8 |
| Cenchrus spinifex | Cav. | Poaceae | 8 |
| Centella erecta | (L.f.) Fernald | Apiaceae | 8 |
| Centrosema virginianum | (L.) Benth. | Fabaceae | 8 |
| Cephalanthus occidentalis | L. | Rubiaceae | 8 |
| Cephalanthus salicifolius | Bonpl. | Rubiaceae | 8 |
| Cerastium brachypodum | (Engelm. ex A.Gray) B.L.Rob. | Caryophyllaceae | 8 |
| Cerastium nutans | Raf. | Caryophyllaceae | 8 |
| Ceratophyllum demersum | L. | Ceratophyllaceae | 8 |
| Ceratophyllum echinatum | A.Gray | Ceratophyllaceae | 8 |
| Cercis canadensis | L. | Fabaceae | 8 |
| Cercocarpus breviflorus | A.Gray | Rosaceae | 8 |
| Cercocarpus montanus | Raf. | Rosaceae | 8 |
| Cevallia sinuata | Lag. | Loasaceae | 8 |
| Chaerophyllum tainturieri | Hook. | Apiaceae | 8 |
| Chaetopappa asteroides | (Nutt.) DC. | Asteraceae | 8 |
| Chaetopappa bellidifolia | (A.Gray & Engelm.) Shinners | Asteraceae | 8 |
| Chaetopappa effusa | (A.Gray) Shinners | Asteraceae | 8 |
| Chaetopappa ericoides | (Torr.) G.L.Nesom | Asteraceae | 8 |
| Chamaecrista calycioides | (DC. ex Collad.) Greene | Fabaceae | 8 |
| Chamaecrista fasciculata | (Michx.) Greene | Fabaceae | 8 |
| Chamaecrista flexuosa | (L.) Greene | Fabaceae | 8 |
| Chamaecrista greggii | (A.Gray) Pollard ex A.Heller | Fabaceae | 8 |
| Chamaecrista nictitans | (L.) Moench | Fabaceae | 8 |
| Chamaesaracha coniodes | (Moric. ex Dunal) Benth. & Hook.f. ex B.D.Jacks. | Solanaceae | 8 |
| Chamaesaracha coronopus | (Dunal) A.Gray | Solanaceae | 8 |
| Chamaesaracha edwardsiana | Averett | Solanaceae | 8 |
| Chamaesaracha pallida | Averett | Solanaceae | 8 |
| Chaptalia texana | Greene | Asteraceae | 8 |
| Chaptalia tomentosa | Vent. | Asteraceae | 8 |
| Chasmanthium latifolium | (Michx.) H.O.Yates | Poaceae | 8 |
| Chasmanthium laxum | (L.) H.O.Yates | Poaceae | 8 |
| Cheilanthes leucopoda | Link | Pteridaceae | 8 |
| Chenopodium berlandieri | Moq. | Chenopodiaceae | 8 |
| Chenopodium fremontii | S.Watson | Chenopodiaceae | 8 |
| Chenopodium incanum | (S.Watson) A.Heller | Chenopodiaceae | 8 |
| Chenopodium leptophyllum | (Nutt. ex Moq.) B.D.Jacks. | Chenopodiaceae | 8 |
| Chilopsis linearis | (Cav.) Sweet | Bignoniaceae | 8 |
| Chiococca alba | (L.) Hitchc. | Rubiaceae | 8 |
| Chionanthus virginicus | L. | Oleaceae | 8 |
| Chloracantha spinosa | (Benth.) G.L.Nesom | Asteraceae | 8 |
| Chloris andropogonoides | E.Fourn. | Poaceae | 8 |
| Chloris cucullata | Bisch. | Poaceae | 8 |
| Chloris verticillata | Nutt. | Poaceae | 8 |
| Chloris virgata | Sw. | Poaceae | 8 |
| Choisya dumosa | (Torr. & A.Gray) A.Gray | Rutaceae | 8 |
| Chromolaena odorata | (L.) R.M.King & H.Rob. | Asteraceae | 8 |
| Chrysactinia mexicana | A.Gray | Asteraceae | 8 |
| Chrysopogon pauciflorus | (Chapm.) Benth. ex Vasey | Poaceae | 8 |
| Chrysopsis mariana | Elliott | Asteraceae | 8 |
| Chthamalia biflora | (Raf.) Decne. | Apocynaceae | 8 |
| Chthamalia cynanchoides | (Engelm. & Gray) Morillo | Apocynaceae | 8 |
| Chthamalia parviflora | (Torr.) L.O.Alvarado & E.B.Cortez | Apocynaceae | 8 |
| Chthamalia producta | (Torr.) L.O.Alvarado & E.B.Cortez | Apocynaceae | 8 |
| Cicuta maculata | L. | Apiaceae | 8 |
| Cienfuegosia drummondii | (A.Gray) Lewton | Malvaceae | 8 |
| Cinna arundinacea | L. | Poaceae | 8 |
| Cirsium altissimum | (L.) Hill | Asteraceae | 8 |
| Cirsium carolinianum | (Walter) Fernald & B.G.Schub. | Asteraceae | 8 |
| Cirsium engelmannii | Rydb. | Asteraceae | 8 |
| Cirsium horridulum | Michx. | Asteraceae | 8 |
| Cirsium muticum | Michx. | Asteraceae | 8 |
| Cirsium neomexicanum | A.Gray | Asteraceae | 8 |
| Cirsium ochrocentrum | A.Gray | Asteraceae | 8 |
| Cirsium texanum | Buckley | Asteraceae | 8 |
| Cirsium undulatum | (Nutt.) Spreng. | Asteraceae | 8 |
| Cirsium wheeleri | Petr. | Asteraceae | 8 |
| Cissus trifoliata | (L.) L. | Vitaceae | 8 |
| Citharexylum berlandieri | B.L.Rob. | Verbenaceae | 8 |
| Citharexylum brachyanthum | (A.Gray ex Hemsl.) A.Gray | Verbenaceae | 8 |
| Cladium mariscoides | (Muhl.) Torr. | Cyperaceae | 8 |
| Cladium mariscus | (L.) Pohl | Cyperaceae | 8 |
| Clappia suaedifolia | A.Gray | Asteraceae | 8 |
| Claytonia virginica | L. | Montiaceae | 8 |
| Clematis carrizoensis | D.Estes | Ranunculaceae | 8 |
| Clematis columbiana | (Nutt.) Torr. & A.Gray | Ranunculaceae | 8 |
| Clematis crispa | L. | Ranunculaceae | 8 |
| Clematis drummondii | Torr. & A.Gray | Ranunculaceae | 8 |
| Clematis ligusticifolia | Nutt. | Ranunculaceae | 8 |
| Clematis pitcheri | Torr. & A.Gray | Ranunculaceae | 8 |
| Clematis texensis | Buckley | Ranunculaceae | 8 |
| Clematis versicolor | Small ex Rydb. | Ranunculaceae | 8 |
| Clematis virginiana | L. | Ranunculaceae | 8 |
| Cleome dodecandra | L. | Cleomaceae | 8 |
| Cleome erosa | (Nutt.) Eaton | Cleomaceae | 8 |
| Cleome jamesii | (Torr. & A.Gray) Govaerts | Cleomaceae | 8 |
| Cleome uniglandulosa | Cav. | Cleomaceae | 8 |
| Cleomella longipes | Torr. | Cleomaceae | 8 |
| Cleomella multicaulis | (DC.) J.C.Hall & Roalson | Cleomaceae | 8 |
| Cleomella refracta | (Engelm.) J.C.Hall & Roalson | Cleomaceae | 8 |
| Cleomella serrulata | (Pursh) Roalson & J.C.Hall | Cleomaceae | 8 |
| Clethra alnifolia | L. | Clethraceae | 8 |
| Clinopodium arkansanum | (Nutt.) House | Lamiaceae | 8 |
| Clinopodium brownei | (Sw.) Kuntze | Lamiaceae | 8 |
| Clinopodium glabellum | (Michx.) Kuntze | Lamiaceae | 8 |
| Clitoria mariana | L. | Fabaceae | 8 |
| Cnidoscolus texanus | Small | Euphorbiaceae | 8 |
| Cochemiea grahamii | (Engelm.) Doweld | Cactaceae | 8 |
| Cochlospermum wrightii | (A.Gray) Byng & Christenh. | Bixaceae | 8 |
| Coleataenia anceps | (Michx.) Soreng | Poaceae | 8 |
| Coleataenia longifolia | (Torr.) Soreng | Poaceae | 8 |
| Coleataenia rigidula | (Bosc ex Nees) LeBlond | Poaceae | 8 |
| Coleataenia tenera | (Beyr. ex Trin.) Soreng | Poaceae | 8 |
| Collinsia verna | Nutt. | Plantaginaceae | 8 |
| Collinsia violacea | Nutt. | Plantaginaceae | 8 |
| Cologania angustifolia | Kunth | Fabaceae | 8 |
| Colubrina greggii | S.Watson | Rhamnaceae | 8 |
| Colubrina texensis | (Torr. & A.Gray) A.Gray | Rhamnaceae | 8 |
| Comandra umbellata | (L.) Nutt. | Santalaceae | 8 |
| Commelina dianthifolia | Redouté | Commelinaceae | 8 |
| Commelina erecta | L. | Commelinaceae | 8 |
| Commelina virginica | L. | Commelinaceae | 8 |
| Condalia correllii | M.C.Johnst. | Rhamnaceae | 8 |
| Condalia ericoides | (A.Gray) M.C.Johnst. | Rhamnaceae | 8 |
| Condalia hookeri | M.C.Johnst. | Rhamnaceae | 8 |
| Condalia spathulata | A.Gray | Rhamnaceae | 8 |
| Condalia viridis | I.M.Johnst. | Rhamnaceae | 8 |
| Condalia warnockii | M.C.Johnst. | Rhamnaceae | 8 |
| Conocarpus erectus | L. | Combretaceae | 8 |
| Conoclinium betonicifolium | (Mill.) R.M.King & H.Rob. | Asteraceae | 8 |
| Conoclinium coelestinum | DC. | Asteraceae | 8 |
| Conoclinium greggii | Small | Asteraceae | 8 |
| Conopholis alpina | Liebm. | Orobanchaceae | 8 |
| Convolvulus crenatifolius | Ruiz & Pav. | Convolvulaceae | 8 |
| Convolvulus equitans | Benth. | Convolvulaceae | 8 |
| Conyza ramosissima | Cronquist | Asteraceae | 8 |
| Corallorhiza maculata | Raf. | Orchidaceae | 8 |
| Corallorhiza odontorhiza | (Willd.) Nutt. | Orchidaceae | 8 |
| Corallorhiza striata | Lindl. | Orchidaceae | 8 |
| Corallorhiza wisteriana | Conrad | Orchidaceae | 8 |
| Cordia boissieri | A.DC. | Cordiaceae | 8 |
| Cordylanthus wrightii | A.Gray | Orobanchaceae | 8 |
| Coreopsis basalis | (A.Dietr.) S.F.Blake | Asteraceae | 8 |
| Coreopsis grandiflora | Hogg ex Sweet | Asteraceae | 8 |
| Coreopsis lanceolata | L. | Asteraceae | 8 |
| Coreopsis nuecensis | A.Heller | Asteraceae | 8 |
| Coreopsis pubescens | Elliott | Asteraceae | 8 |
| Coreopsis tinctoria | Nutt. | Asteraceae | 8 |
| Coreopsis tripteris | L. | Asteraceae | 8 |
| Cornus drummondii | C.A.Mey. | Cornaceae | 8 |
| Cornus florida | L. | Cornaceae | 8 |
| Cornus foemina | Mill. | Cornaceae | 8 |
| Cornus racemosa | Lam. | Cornaceae | 8 |
| Corydalis aurea | Willd. | Papaveraceae | 8 |
| Corydalis curvisiliqua | (A.Gray) Engelm. ex A.Gray | Papaveraceae | 8 |
| Corydalis micrantha | (Engelm. ex A.Gray) A.Gray ex J.M.Coult. | Papaveraceae | 8 |
| Coryphantha echinus | (Engelm.) Britton & Rose | Cactaceae | 8 |
| Coryphantha nickelsiae | (K.Brandegee) Britton & Rose | Cactaceae | 8 |
| Coryphantha robustispina | (Schott ex Engelm.) Britton & Rose | Cactaceae | 8 |
| Coryphantha sulcata | (Engelm.) Britton & Rose | Cactaceae | 8 |
| Cotinus obovatus | Raf. | Anacardiaceae | 8 |
| Cottea pappophoroides | Kunth | Poaceae | 8 |
| Cottsia gracilis | (A.Gray) W.R.Anderson & C.Davis | Malpighiaceae | 8 |
| Coursetia axillaris | J.M.Coult. & Rose | Fabaceae | 8 |
| Crataegus crus-galli | L. | Rosaceae | 8 |
| Crataegus mollis | (Torr. & A.Gray) Scheele | Rosaceae | 8 |
| Crataegus opaca | Hook. & Arn. | Rosaceae | 8 |
| Crataegus spathulata | Michx. | Rosaceae | 8 |
| Crataegus tracyi | Ashe ex Eggl. | Rosaceae | 8 |
| Crataegus uniflora | Münchh. | Rosaceae | 8 |
| Crataegus viridis | L. | Rosaceae | 8 |
| Cressa truxillensis | Kunth | Convolvulaceae | 8 |
| Crinum americanum | L. | Amaryllidaceae | 8 |
| Crocanthemum carolinianum | (Walter) Spach | Cistaceae | 8 |
| Crocanthemum georgianum | (Chapm.) Barnhart | Cistaceae | 8 |
| Crocanthemum glomeratum | (Lag.) Janch. | Cistaceae | 8 |
| Crocanthemum rosmarinifolium | (Pursh) Janch. | Cistaceae | 8 |
| Croptilon divaricatum | (Nutt.) Raf. | Asteraceae | 8 |
| Croptilon hookerianum | (Torr. & A.Gray) House | Asteraceae | 8 |
| Crotalaria pumila | Ortega | Fabaceae | 8 |
| Crotalaria purshii | DC. | Fabaceae | 8 |
| Crotalaria sagittalis | L. | Fabaceae | 8 |
| Croton alabamensis | E.A.Sm. ex Chapm. | Euphorbiaceae | 8 |
| Croton argyranthemus | Michx. | Euphorbiaceae | 8 |
| Croton bigbendensis | B.L.Turner | Euphorbiaceae | 8 |
| Croton capitatus | Michx. | Euphorbiaceae | 8 |
| Croton ciliatoglandulifer | Ortega | Euphorbiaceae | 8 |
| Croton cortesianus | Kunth | Euphorbiaceae | 8 |
| Croton coryi | Croizat | Euphorbiaceae | 8 |
| Croton dioicus | Cav. | Euphorbiaceae | 8 |
| Croton fruticulosus | Torr. | Euphorbiaceae | 8 |
| Croton glandulosus | L. | Euphorbiaceae | 8 |
| Croton heptalon | (Kuntze) B.W.van Ee & P.E.Berry | Euphorbiaceae | 8 |
| Croton humilis | L. | Euphorbiaceae | 8 |
| Croton incanus | Kunth | Euphorbiaceae | 8 |
| Croton leucophyllus | Müll.Arg. | Euphorbiaceae | 8 |
| Croton lindheimeri | (Engelm. & A.Gray) Alph.Wood | Euphorbiaceae | 8 |
| Croton lindheimerianus | Scheele | Euphorbiaceae | 8 |
| Croton michauxii | G.L.Webster | Euphorbiaceae | 8 |
| Croton monanthogynus | Michx. | Euphorbiaceae | 8 |
| Croton parksii | Croizat | Euphorbiaceae | 8 |
| Croton pottsii | (Klotzsch) Müll.Arg. | Euphorbiaceae | 8 |
| Croton punctatus | Jacq. | Euphorbiaceae | 8 |
| Croton suaveolens | Torr. | Euphorbiaceae | 8 |
| Croton texensis | (Klotzsch) Müll.Arg. | Euphorbiaceae | 8 |
| Cryptantha barbigera | (A.Gray) Greene | Boraginaceae | 8 |
| Cryptantha crassisepala | (Torr. & A.Gray) Greene | Boraginaceae | 8 |
| Cryptantha minima | Rydb. | Boraginaceae | 8 |
| Cryptantha pterocarya | (Torr.) Greene | Boraginaceae | 8 |
| Cryptantha texana | Greene | Boraginaceae | 8 |
| Cryptotaenia canadensis | (L.) DC. | Apiaceae | 8 |
| Ctenodon viscidulus | (Michx.) D.B.O.S.Cardoso & A.Delgado | Fabaceae | 8 |
| Cucurbita digitata | A.Gray | Cucurbitaceae | 8 |
| Cucurbita foetidissima | Kunth | Cucurbitaceae | 8 |
| Cunila origanoides | (L.) Britton | Lamiaceae | 8 |
| Cuphea viscosissima | Jacq. | Lythraceae | 8 |
| Cuscuta campestris | Yunck. | Convolvulaceae | 8 |
| Cuscuta cephalanthi | Engelm. | Convolvulaceae | 8 |
| Cuscuta compacta | Juss. ex Choisy | Convolvulaceae | 8 |
| Cuscuta coryli | Engelm. | Convolvulaceae | 8 |
| Cuscuta cuspidata | Engelm. | Convolvulaceae | 8 |
| Cuscuta exaltata | Engelm. | Convolvulaceae | 8 |
| Cuscuta glomerata | Choisy | Convolvulaceae | 8 |
| Cuscuta gronovii | Willd. | Convolvulaceae | 8 |
| Cuscuta indecora | Choisy | Convolvulaceae | 8 |
| Cuscuta pentagona | Engelm. | Convolvulaceae | 8 |
| Cuscuta runyonii | Yunck. | Convolvulaceae | 8 |
| Cuscuta umbellata | Kunth | Convolvulaceae | 8 |
| Cyclanthera naudiniana | Cogn. | Cucurbitaceae | 8 |
| Cylindropuntia davisii | (Engelm. & J.M.Bigelow) F.M.Knuth | Cactaceae | 8 |
| Cylindropuntia imbricata | (Haw.) F.M.Knuth | Cactaceae | 8 |
| Cylindropuntia kleiniae | (DC.) F.M.Knuth | Cactaceae | 8 |
| Cylindropuntia leptocaulis | (DC.) F.M.Knuth | Cactaceae | 8 |
| Cylindropuntia tunicata | (Lehm.) F.M.Knuth | Cactaceae | 8 |
| Cymopterus filifolius | (Mathias, Constance & W.L.Theob.) B.L.Turner | Apiaceae | 8 |
| Cymopterus glomeratus | (Nutt.) DC. | Apiaceae | 8 |
| Cymopterus hallii | (A.Gray) B.L.Turner | Apiaceae | 8 |
| Cymopterus lemmonii | (J.M.Coult. & Rose) Dorn | Apiaceae | 8 |
| Cynanchum laeve | (Michx.) Pers. | Apocynaceae | 8 |
| Cynosciadium digitatum | DC. | Apiaceae | 8 |
| Cyperus acuminatus | Torr. & Hook. | Cyperaceae | 8 |
| Cyperus aggregatus | (Willd.) Endl. | Cyperaceae | 8 |
| Cyperus articulatus | L. | Cyperaceae | 8 |
| Cyperus bipartitus | Torr. | Cyperaceae | 8 |
| Cyperus blepharoleptos | Steud. | Cyperaceae | 8 |
| Cyperus brevifolius | (Rottb.) Hassk. | Cyperaceae | 8 |
| Cyperus compressus | L. | Cyperaceae | 8 |
| Cyperus croceus | Vahl | Cyperaceae | 8 |
| Cyperus echinatus | (L.) Alph.Wood | Cyperaceae | 8 |
| Cyperus eragrostis | Lam. | Cyperaceae | 8 |
| Cyperus esculentus | L. | Cyperaceae | 8 |
| Cyperus fendlerianus | Boeckeler | Cyperaceae | 8 |
| Cyperus filiculmis | Vahl | Cyperaceae | 8 |
| Cyperus flavescens | L. | Cyperaceae | 8 |
| Cyperus haspan | L. | Cyperaceae | 8 |
| Cyperus hermaphroditus | (Jacq.) Standl. | Cyperaceae | 8 |
| Cyperus laevigatus | L. | Cyperaceae | 8 |
| Cyperus lanceolatus | Poir. | Cyperaceae | 8 |
| Cyperus lupulinus | (Biehler) Marcks | Cyperaceae | 8 |
| Cyperus melanostachyus | Kunth | Cyperaceae | 8 |
| Cyperus ochraceus | Vahl | Cyperaceae | 8 |
| Cyperus odoratus | L. | Cyperaceae | 8 |
| Cyperus plukenetii | Fernald | Cyperaceae | 8 |
| Cyperus polystachyos | Rottb. | Cyperaceae | 8 |
| Cyperus pseudothyrsiflorus | (Kük.) R.Carter & S.D.Jones | Cyperaceae | 8 |
| Cyperus pseudovegetus | Steud. | Cyperaceae | 8 |
| Cyperus refractus | Engelm. ex Boeckeler | Cyperaceae | 8 |
| Cyperus retroflexus | Buckley | Cyperaceae | 8 |
| Cyperus retrorsus | Chapm. | Cyperaceae | 8 |
| Cyperus schweinitzii | Torr. | Cyperaceae | 8 |
| Cyperus seslerioides | Kunth | Cyperaceae | 8 |
| Cyperus sesquiflorus | (Torr.) Mattf. & Kük. | Cyperaceae | 8 |
| Cyperus sphaerolepis | Boeckeler | Cyperaceae | 8 |
| Cyperus squarrosus | L. | Cyperaceae | 8 |
| Cyperus strigosus | L. | Cyperaceae | 8 |
| Cyperus subsquarrosus | (Muhl.) Bauters | Cyperaceae | 8 |
| Cyperus surinamensis | Rottb. | Cyperaceae | 8 |
| Cyperus thyrsiflorus | Jungh. | Cyperaceae | 8 |
| Cyperus virens | Michx. | Cyperaceae | 8 |
| Cyphomeris gypsophiloides | (M.Martens & Galeotti) Standl. | Nyctaginaceae | 8 |
| Cypripedium kentuckiense | C.F.Reed | Orchidaceae | 8 |
| Cyrilla racemiflora | L. | Cyrillaceae | 8 |
| Cystopteris bulbifera | (L.) Bernh. | Cystopteridaceae | 8 |
| Cystopteris fragilis | (L.) Bernh. | Cystopteridaceae | 8 |
| Cystopteris reevesiana | Lellinger | Cystopteridaceae | 8 |
| Dalea aurea | Nutt. ex Pursh | Fabaceae | 8 |
| Dalea bicolor | Humb. & Bonpl. ex Willd. | Fabaceae | 8 |
| Dalea candida | Willd. | Fabaceae | 8 |
| Dalea compacta | Spreng. | Fabaceae | 8 |
| Dalea cylindriceps | Barneby | Fabaceae | 8 |
| Dalea emarginata | (Torr. & A.Gray) Shinners | Fabaceae | 8 |
| Dalea enneandra | Nutt. | Fabaceae | 8 |
| Dalea formosa | Torr. | Fabaceae | 8 |
| Dalea frutescens | A.Gray | Fabaceae | 8 |
| Dalea greggii | A.Gray | Fabaceae | 8 |
| Dalea hallii | A.Gray | Fabaceae | 8 |
| Dalea jamesii | (Torr.) Torr. & A.Gray | Fabaceae | 8 |
| Dalea lanata | Spreng. | Fabaceae | 8 |
| Dalea lasiathera | A.Gray | Fabaceae | 8 |
| Dalea leporina | (Aiton) Bullock | Fabaceae | 8 |
| Dalea multiflora | (Nutt.) Shinners | Fabaceae | 8 |
| Dalea nana | Torr. ex A.Gray | Fabaceae | 8 |
| Dalea neomexicana | (A.Gray) Cory | Fabaceae | 8 |
| Dalea obovata | (Torr. & A.Gray) Shinners | Fabaceae | 8 |
| Dalea phleoides | (Torr. & A.Gray) Shinners | Fabaceae | 8 |
| Dalea pogonathera | A.Gray | Fabaceae | 8 |
| Dalea polygonoides | A.Gray | Fabaceae | 8 |
| Dalea purpurea | Vent. | Fabaceae | 8 |
| Dalea reverchonii | (S.Watson) Shinners | Fabaceae | 8 |
| Dalea rubescens | S.Watson | Fabaceae | 8 |
| Dalea tenuifolia | (A.Gray) Shinners | Fabaceae | 8 |
| Dalea tenuis | (J.M.Coult.) Shinners | Fabaceae | 8 |
| Dalea villosa | (Nutt.) Spreng. | Fabaceae | 8 |
| Dalea wrightii | A.Gray | Fabaceae | 8 |
| Danthonia spicata | (L.) Roem. & Schult. | Poaceae | 8 |
| Dasistoma macrophylla | (Nutt.) Raf. | Orobanchaceae | 8 |
| Dasylirion leiophyllum | Engelm. ex Trel. | Asparagaceae | 8 |
| Dasylirion texanum | Scheele | Asparagaceae | 8 |
| Dasylirion wheeleri | S.Watson ex Rothr. | Asparagaceae | 8 |
| Datura innoxia | Mill. | Solanaceae | 8 |
| Datura quercifolia | Kunth | Solanaceae | 8 |
| Datura wrightii | Regel | Solanaceae | 8 |
| Daucus pusillus | Michx. | Apiaceae | 8 |
| Dayia havardii | (A.Gray) J.M.Porter | Polemoniaceae | 8 |
| Decodon verticillatus | (L.) Elliott | Lythraceae | 8 |
| Delphinium carolinianum | Walter | Ranunculaceae | 8 |
| Delphinium madrense | S.Watson | Ranunculaceae | 8 |
| Delphinium wootonii | Rydb. | Ranunculaceae | 8 |
| Dermatophyllum secundiflorum | (Ortega) Gandhi & Reveal | Fabaceae | 8 |
| Descurainia incisa | (Engelm.) Britton | Brassicaceae | 8 |
| Descurainia pinnata | (Walter) Britton | Brassicaceae | 8 |
| Desmanthus acuminatus | Benth. | Fabaceae | 8 |
| Desmanthus cooleyi | (Eaton) Trel. ex Branner & Coville | Fabaceae | 8 |
| Desmanthus illinoensis | (Michx.) MacMill. ex B.L.Rob. & Fernald | Fabaceae | 8 |
| Desmanthus leptolobus | Torr. & A.Gray | Fabaceae | 8 |
| Desmanthus reticulatus | Benth. | Fabaceae | 8 |
| Desmanthus velutinus | Scheele | Fabaceae | 8 |
| Desmanthus virgatus | (L.) Willd. | Fabaceae | 8 |
| Desmodium canadense | (L.) DC. | Fabaceae | 8 |
| Desmodium canescens | (L.) DC. | Fabaceae | 8 |
| Desmodium ciliare | (Muhl. ex Willd.) DC. | Fabaceae | 8 |
| Desmodium glabellum | (Michx.) DC. | Fabaceae | 8 |
| Desmodium grahamii | A.Gray | Fabaceae | 8 |
| Desmodium laevigatum | (Nutt.) DC. | Fabaceae | 8 |
| Desmodium lindheimeri | Vail | Fabaceae | 8 |
| Desmodium lineatum | DC. | Fabaceae | 8 |
| Desmodium marilandicum | (L.) DC. | Fabaceae | 8 |
| Desmodium nuttallii | (Schindl.) B.G.Schub. | Fabaceae | 8 |
| Desmodium obtusum | (Muhl. ex Willd.) DC. | Fabaceae | 8 |
| Desmodium paniculatum | (L.) DC. | Fabaceae | 8 |
| Desmodium procumbens | (Mill.) C.L.Hitchc. | Fabaceae | 8 |
| Desmodium psilophyllum | Schltdl. | Fabaceae | 8 |
| Desmodium rotundifolium | DC. | Fabaceae | 8 |
| Desmodium sessilifolium | (Torr. ex M.A.Curtis) Torr. & A.Gray | Fabaceae | 8 |
| Desmodium tweedyi | Britton | Fabaceae | 8 |
| Desmodium viridiflorum | (L.) DC. | Fabaceae | 8 |
| Dianthera americana | L. | Acanthaceae | 8 |
| Diaperia candida | (Torr. & A.Gray) Benth. & Hook.f. | Asteraceae | 8 |
| Diaperia prolifera | (Nutt. ex DC.) Nutt. | Asteraceae | 8 |
| Diaperia verna | (Raf.) Morefield | Asteraceae | 8 |
| Diarrhena americana | P.Beauv. | Poaceae | 8 |
| Dichanthelium aciculare | (Desv.) Gould & C.A.Clark | Poaceae | 8 |
| Dichanthelium acuminatum | (Sw.) Gould & C.A.Clark | Poaceae | 8 |
| Dichanthelium boscii | (Poir.) Gould & C.A.Clark | Poaceae | 8 |
| Dichanthelium clandestinum | (L.) Gould | Poaceae | 8 |
| Dichanthelium commonsianum | (Ashe) Freckmann | Poaceae | 8 |
| Dichanthelium commutatum | (Schult.) Gould | Poaceae | 8 |
| Dichanthelium consanguineum | (Kunth) Gould & C.A.Clark | Poaceae | 8 |
| Dichanthelium curtifolium | (Nash) LeBlond | Poaceae | 8 |
| Dichanthelium depauperatum | (Muhl.) Gould | Poaceae | 8 |
| Dichanthelium dichotomum | (L.) Gould | Poaceae | 8 |
| Dichanthelium ensifolium | (Baldwin ex Elliott) Gould | Poaceae | 8 |
| Dichanthelium filiramum | (Ashe) LeBlond | Poaceae | 8 |
| Dichanthelium lanuginosum | (Elliott) Gould | Poaceae | 8 |
| Dichanthelium latifolium | (L.) Harvill | Poaceae | 8 |
| Dichanthelium laxiflorum | (Lam.) Gould | Poaceae | 8 |
| Dichanthelium leucothrix | (Nash) Freckmann | Poaceae | 8 |
| Dichanthelium lindheimeri | (Nash) Gould | Poaceae | 8 |
| Dichanthelium linearifolium | (Scribn.) Gould | Poaceae | 8 |
| Dichanthelium longiligulatum | (Nash) Freckmann | Poaceae | 8 |
| Dichanthelium lucidum | (Ashe) LeBlond | Poaceae | 8 |
| Dichanthelium microcarpon | (Muhl. ex Elliott) Mohlenbr. | Poaceae | 8 |
| Dichanthelium neuranthum | (Griseb.) LeBlond | Poaceae | 8 |
| Dichanthelium oligosanthes | (Schult.) Gould | Poaceae | 8 |
| Dichanthelium ovale | (Elliott) Gould & C.A.Clark | Poaceae | 8 |
| Dichanthelium polyanthes | (Schult.) Mohlenbr. | Poaceae | 8 |
| Dichanthelium portoricense | (Desv.) B.F.Hansen & Wunderlin | Poaceae | 8 |
| Dichanthelium praecocius | (Hitchc. & Chase) Mohlenbr. | Poaceae | 8 |
| Dichanthelium ravenelii | (Scribn. & Merr.) Gould | Poaceae | 8 |
| Dichanthelium roanokense | (Ashe) LeBlond | Poaceae | 8 |
| Dichanthelium scabriusculum | (Elliott) Gould & C.A.Clark | Poaceae | 8 |
| Dichanthelium scoparium | (Lam.) Gould | Poaceae | 8 |
| Dichanthelium sphaerocarpon | (Elliott) Gould | Poaceae | 8 |
| Dichanthelium tenue | (Muhl.) Freckmann & Lelong | Poaceae | 8 |
| Dichanthelium yadkinense | (Ashe) Mohlenbr. | Poaceae | 8 |
| Dichondra argentea | Humb. & Bonpl. ex Willd. | Convolvulaceae | 8 |
| Dichondra brachypoda | Wooton & Standl. | Convolvulaceae | 8 |
| Dichondra carolinensis | Michx. | Convolvulaceae | 8 |
| Dichondra recurvata | Tharp & M.C.Johnst. | Convolvulaceae | 8 |
| Dichromanthus cinnabarinus | (La Llave & Lex.) Garay | Orchidaceae | 8 |
| Dichromanthus michuacanus | (La Llave & Lex.) Salazar & Soto Arenas | Orchidaceae | 8 |
| Dicliptera brachiata | Spreng. | Acanthaceae | 8 |
| Dicliptera sexangularis | (L.) Juss. | Acanthaceae | 8 |
| Dicranocarpus parviflorus | A.Gray | Asteraceae | 8 |
| Dieteria canescens | (Pursh) Nutt. | Asteraceae | 8 |
| Digitaria californica | (Benth.) Henrard | Poaceae | 8 |
| Digitaria cognata | (Schult.) Pilg. | Poaceae | 8 |
| Digitaria filiformis | (L.) Koeler | Poaceae | 8 |
| Digitaria insularis | (L.) Mez ex Ekman | Poaceae | 8 |
| Dimorphocarpa candicans | (Raf.) Rollins | Brassicaceae | 8 |
| Diodia virginiana | L. | Rubiaceae | 8 |
| Dioscorea villosa | L. | Dioscoreaceae | 8 |
| Diospyros texana | Scheele | Ebenaceae | 8 |
| Diospyros virginiana | L. | Ebenaceae | 8 |
| Diplachne fusca | (L.) P.Beauv. | Poaceae | 8 |
| Disakisperma dubium | (Kunth) P.M.Peterson & N.Snow | Poaceae | 8 |
| Distichlis littoralis | (Engelm.) H.L.Bell & Columbus | Poaceae | 8 |
| Distichlis spicata | (L.) Greene | Poaceae | 8 |
| Distimake dissectus | (Jacq.) A.R.Simões & Staples | Convolvulaceae | 8 |
| Ditaxis humilis | (Engelm. & A.Gray) Pax | Euphorbiaceae | 8 |
| Ditaxis mercurialina | (Nutt.) J.M.Coult. | Euphorbiaceae | 8 |
| Ditaxis serrata | (Torr.) A.Heller | Euphorbiaceae | 8 |
| Ditaxis simulans | (J.W.Ingram) Radcl.-Sm. & Govaerts | Euphorbiaceae | 8 |
| Ditrysinia fruticosa | (W.Bartram) Govaerts & Frodin | Euphorbiaceae | 8 |
| Doellingeria sericocarpoides | Small | Asteraceae | 8 |
| Draba nemorosa | L. | Brassicaceae | 8 |
| Drosera brevifolia | Pursh | Droseraceae | 8 |
| Drosera capillaris | Poir. | Droseraceae | 8 |
| Drosera intermedia | Hayne | Droseraceae | 8 |
| Drymaria leptophylla | (Cham. & Schltdl.) Fenzl ex Rohrb. | Caryophyllaceae | 8 |
| Drymaria molluginea | (Ser.) Didr. | Caryophyllaceae | 8 |
| Dryopetalon runcinatum | A.Gray | Brassicaceae | 8 |
| Dryopteris filix-mas | (L.) Schott | Dryopteridaceae | 8 |
| Dryopteris ludoviciana | (Kunze) Small | Dryopteridaceae | 8 |
| Dulichium arundinaceum | (L.) Britton | Cyperaceae | 8 |
| Dyschoriste crenulata | Kobuski | Acanthaceae | 8 |
| Dyschoriste decumbens | (A.Gray) Kuntze | Acanthaceae | 8 |
| Dyschoriste linearis | (Torr. & A.Gray) Kuntze | Acanthaceae | 8 |
| Dysodiopsis tagetoides | Rydb. | Asteraceae | 8 |
| Dysphania ambrosioides | (L.) Mosyakin & Clemants | Chenopodiaceae | 8 |
| Dyssodia papposa | (Vent.) Hitchc. | Asteraceae | 8 |
| Ebenopsis ebano | (Berland.) Barneby & J.W.Grimes | Fabaceae | 8 |
| Echeandia flavescens | (Schult. & Schult.f.) Cruden | Asparagaceae | 8 |
| Echeandia texensis | Cruden | Asparagaceae | 8 |
| Echeveria strictiflora | A.Gray | Crassulaceae | 8 |
| Echinacea angustifolia | DC. | Asteraceae | 8 |
| Echinacea atrorubens | (Nutt.) Nutt. | Asteraceae | 8 |
| Echinacea pallida | (Nutt.) Nutt. | Asteraceae | 8 |
| Echinacea purpurea | (L.) Moench | Asteraceae | 8 |
| Echinacea sanguinea | Nutt. | Asteraceae | 8 |
| Echinocereus berlandieri | (Engelm.) Haage | Cactaceae | 8 |
| Echinocereus coccineus | Engelm. | Cactaceae | 8 |
| Echinocereus fendleri | (Engelm.) Sencke ex J.N.Haage | Cactaceae | 8 |
| Echinochloa muricata | (P.Beauv.) Fernald | Poaceae | 8 |
| Echinochloa walteri | (Pursh) A.Heller | Poaceae | 8 |
| Echinodorus berteroi | (Spreng.) Fassett | Alismataceae | 8 |
| Echinopepon wrightii | (A.Gray) S.Watson | Cucurbitaceae | 8 |
| Eclipta prostrata | (L.) L. | Asteraceae | 8 |
| Edrastima uniflora | (L.) Raf. | Rubiaceae | 8 |
| Ehretia anacua | (Terán & Berland.) I.M.Johnst. | Ehretiaceae | 8 |
| Elaeagnus commutata | Bernh. ex Rydb. | Elaeagnaceae | 8 |
| Elatine americana | (Pursh) Arn. | Elatinaceae | 8 |
| Elatine brachysperma | A.Gray | Elatinaceae | 8 |
| Eleocharis acicularis | (L.) Roem. & Schult. | Cyperaceae | 8 |
| Eleocharis atropurpurea | (Retz.) J.Presl & C.Presl | Cyperaceae | 8 |
| Eleocharis baldwinii | (Torr.) Chapm. | Cyperaceae | 8 |
| Eleocharis cellulosa | Torr. | Cyperaceae | 8 |
| Eleocharis compressa | Sull. | Cyperaceae | 8 |
| Eleocharis elongata | Chapm. | Cyperaceae | 8 |
| Eleocharis engelmannii | Steud. | Cyperaceae | 8 |
| Eleocharis equisetoides | (Elliott) Torr. | Cyperaceae | 8 |
| Eleocharis erythropoda | Steud. | Cyperaceae | 8 |
| Eleocharis geniculata | (L.) Roem. & Schult. | Cyperaceae | 8 |
| Eleocharis interstincta | (Vahl) Roem. & Schult. | Cyperaceae | 8 |
| Eleocharis macrostachya | Britton | Cyperaceae | 8 |
| Eleocharis montana | (Kunth) Roem. & Schult. | Cyperaceae | 8 |
| Eleocharis montevidensis | Kunth | Cyperaceae | 8 |
| Eleocharis obtusa | (Willd.) Schult. | Cyperaceae | 8 |
| Eleocharis palustris | (L.) Roem. & Schult. | Cyperaceae | 8 |
| Eleocharis quadrangulata | (Michx.) Roem. & Schult. | Cyperaceae | 8 |
| Eleocharis rostellata | (Torr.) Torr. | Cyperaceae | 8 |
| Eleocharis tuberculosa | (Michx.) Roem. & Schult. | Cyperaceae | 8 |
| Elephantopus carolinianus | Raeusch. | Asteraceae | 8 |
| Elephantopus nudatus | A.Gray | Asteraceae | 8 |
| Elephantopus tomentosus | L. | Asteraceae | 8 |
| Elionurus tripsacoides | Willd. | Poaceae | 8 |
| Ellisia nyctelea | (L.) L. | Hydrophyllaceae | 8 |
| Elymus canadensis | L. | Poaceae | 8 |
| Elymus elymoides | (Raf.) Swezey | Poaceae | 8 |
| Elymus glaucus | Buckley | Poaceae | 8 |
| Elymus interruptus | Buckley | Poaceae | 8 |
| Elymus longifolius | (J.G.Sm.) Gould | Poaceae | 8 |
| Elymus macgregorii | R.E.Brooks & J.J.N.Campb. | Poaceae | 8 |
| Elymus smithii | (Rydb.) Gould | Poaceae | 8 |
| Elymus villosus | Muhl. ex Willd. | Poaceae | 8 |
| Elymus violaceus | (Hornem.) J.Feilberg | Poaceae | 8 |
| Elymus virginicus | L. | Poaceae | 8 |
| Elytraria bromoides | Oerst. | Acanthaceae | 8 |
| Elytraria imbricata | (Vahl) Pers. | Acanthaceae | 8 |
| Emilia fosbergii | Nicolson | Asteraceae | 8 |
| Enemion biternatum | Raf. | Ranunculaceae | 8 |
| Engelmannia peristenia | (Raf.) Goodman & C.A.Lawson | Asteraceae | 8 |
| Enneapogon desvauxii | P.Beauv. | Poaceae | 8 |
| Ephedra antisyphilitica | Berland. ex C.A.Mey. | Ephedraceae | 8 |
| Ephedra aspera | Engelm. ex S.Watson | Ephedraceae | 8 |
| Ephedra pedunculata | Engelm. ex S.Watson | Ephedraceae | 8 |
| Ephedra torreyana | S.Watson | Ephedraceae | 8 |
| Ephedra trifurca | Torr. ex S.Watson | Ephedraceae | 8 |
| Epifagus virginiana | (L.) Barton | Orobanchaceae | 8 |
| Epilobium ciliatum | Raf. | Onagraceae | 8 |
| Epilobium coloratum | Muhl. ex Willd. | Onagraceae | 8 |
| Epilobium leptophyllum | Raf. | Onagraceae | 8 |
| Epipactis gigantea | Douglas | Orchidaceae | 8 |
| Epithelantha bokei | L.D.Benson | Cactaceae | 8 |
| Epithelantha micromeris | (Engelm.) F.A.C.Weber ex Britton & Rose | Cactaceae | 8 |
| Epixiphium wislizeni | (Engelm. ex A.Gray) Munz | Plantaginaceae | 8 |
| Equisetum arvense | L. | Equisetaceae | 8 |
| Equisetum hyemale | L. | Equisetaceae | 8 |
| Equisetum laevigatum | A.Braun | Equisetaceae | 8 |
| Eragrostis curtipedicellata | Buckley | Poaceae | 8 |
| Eragrostis elliottii | (Elliott) S.Watson | Poaceae | 8 |
| Eragrostis hirsuta | (Michx.) Nees | Poaceae | 8 |
| Eragrostis hypnoides | (Lam.) Britton, Sterns & Poggenb. | Poaceae | 8 |
| Eragrostis intermedia | Hitchc. | Poaceae | 8 |
| Eragrostis pectinacea | (Michx.) Nees | Poaceae | 8 |
| Eragrostis refracta | (Muhl.) Scribn. | Poaceae | 8 |
| Eragrostis reptans | (Michx.) Nees | Poaceae | 8 |
| Eragrostis secundiflora | J.Presl | Poaceae | 8 |
| Eragrostis sessilispica | Buckley | Poaceae | 8 |
| Eragrostis spectabilis | (Pursh) Steud. | Poaceae | 8 |
| Eragrostis trichodes | (Nutt.) Alph.Wood | Poaceae | 8 |
| Erechtites hieraciifolius | (L.) Raf. ex DC. | Asteraceae | 8 |
| Eremocarya micrantha | (Torr.) Greene | Boraginaceae | 8 |
| Eremogone fendleri | (A.Gray) Ikonn. | Caryophyllaceae | 8 |
| Eremothera chamaenerioides | (A.Gray) W.L.Wagner & Hoch | Onagraceae | 8 |
| Erianthus alopecuroides | (L.) Elliott | Poaceae | 8 |
| Erianthus contortus | Baldwin ex Elliott | Poaceae | 8 |
| Erianthus giganteus | (Walter) P.Beauv. | Poaceae | 8 |
| Erianthus strictus | Baldwin | Poaceae | 8 |
| Eriastrum diffusum | (A.Gray) H.Mason | Polemoniaceae | 8 |
| Ericameria laricifolia | (A.Gray) Shinners | Asteraceae | 8 |
| Ericameria linearifolia | (DC.) Urbatsch & Wussow | Asteraceae | 8 |
| Ericameria nauseosa | (Pursh) G.L.Nesom & G.I.Baird | Asteraceae | 8 |
| Erigeron bellidiastrum | Nutt. | Asteraceae | 8 |
| Erigeron canadensis | L. | Asteraceae | 8 |
| Erigeron divergens | Torr. & A.Gray | Asteraceae | 8 |
| Erigeron flagellaris | A.Gray | Asteraceae | 8 |
| Erigeron modestus | A.Gray | Asteraceae | 8 |
| Erigeron philadelphicus | L. | Asteraceae | 8 |
| Erigeron procumbens | (Mill.) G.L.Nesom | Asteraceae | 8 |
| Erigeron pulchellus | Michx. | Asteraceae | 8 |
| Erigeron strigosus | Muhl. ex Willd. | Asteraceae | 8 |
| Erigeron tracyi | Greene | Asteraceae | 8 |
| Eriocaulon compressum | Lam. | Eriocaulaceae | 8 |
| Eriocaulon decangulare | L. | Eriocaulaceae | 8 |
| Eriochloa contracta | Hitchc. | Poaceae | 8 |
| Eriochloa sericea | (Scheele) Munro ex Vasey | Poaceae | 8 |
| Eriocoma arida | (M.E.Jones) Romasch. | Poaceae | 8 |
| Eriocoma hymenoides | (Roem. & Schult.) Rydb. | Poaceae | 8 |
| Eriocoma nelsonii | (Scribn.) Romasch. | Poaceae | 8 |
| Eriogonum abertianum | Torr. | Polygonaceae | 8 |
| Eriogonum alatum | Torr. | Polygonaceae | 8 |
| Eriogonum annuum | Nutt. | Polygonaceae | 8 |
| Eriogonum corymbosum | Benth. | Polygonaceae | 8 |
| Eriogonum greggii | Torr. & A.Gray | Polygonaceae | 8 |
| Eriogonum havardii | S.Watson | Polygonaceae | 8 |
| Eriogonum hemipterum | (Torr. & A.Gray) Torr. ex S.Stokes | Polygonaceae | 8 |
| Eriogonum jamesii | Benth. | Polygonaceae | 8 |
| Eriogonum lachnogynum | Torr. ex Benth. | Polygonaceae | 8 |
| Eriogonum longifolium | Nutt. | Polygonaceae | 8 |
| Eriogonum multiflorum | Benth. | Polygonaceae | 8 |
| Eriogonum nealleyi | J.M.Coult. | Polygonaceae | 8 |
| Eriogonum polycladon | Benth. | Polygonaceae | 8 |
| Eriogonum rotundifolium | Benth. | Polygonaceae | 8 |
| Eriogonum tenellum | Torr. | Polygonaceae | 8 |
| Eriogonum wrightii | Torr. ex Benth. | Polygonaceae | 8 |
| Erioneuron avenaceum | (Kunth) Tateoka | Poaceae | 8 |
| Erioneuron pilosum | (Buckley) Nash | Poaceae | 8 |
| Erodium texanum | A.Gray | Geraniaceae | 8 |
| Eryngium heterophyllum | Engelm. | Apiaceae | 8 |
| Eryngium hookeri | Walp. | Apiaceae | 8 |
| Eryngium integrifolium | Walter | Apiaceae | 8 |
| Eryngium leavenworthii | Torr. & A.Gray | Apiaceae | 8 |
| Eryngium nasturtiifolium | F.Delaroche | Apiaceae | 8 |
| Eryngium prostratum | Nutt. ex DC. | Apiaceae | 8 |
| Eryngium yuccifolium | Michx. | Apiaceae | 8 |
| Erysimum asperum | (Nutt.) DC. | Brassicaceae | 8 |
| Erysimum capitatum | Greene | Brassicaceae | 8 |
| Erythranthe cordata | (Greene) G.L.Nesom | Phrymaceae | 8 |
| Erythranthe geyeri | (Torr.) G.L.Nesom | Phrymaceae | 8 |
| Erythranthe guttata | (DC.) G.L.Nesom | Phrymaceae | 8 |
| Erythranthe inamoena | (Greene) G.L.Nesom | Phrymaceae | 8 |
| Erythranthe rubella | (A.Gray) N.S.Fraga | Phrymaceae | 8 |
| Erythrina herbacea | L. | Fabaceae | 8 |
| Erythronium albidum | Nutt. | Liliaceae | 8 |
| Erythronium mesochoreum | Knerr | Liliaceae | 8 |
| Erythronium rostratum | W.Wolf | Liliaceae | 8 |
| Erythrostemon caudatus | (A.Gray) Gagnon & G.P.Lewis | Fabaceae | 8 |
| Erythrostemon mexicanus | (Rose) Gagnon & G.P.Lewis | Fabaceae | 8 |
| Erythrostemon phyllanthoides | (Standl.) Gagnon & G.P.Lewis | Fabaceae | 8 |
| Eschscholzia californica | Cham. | Papaveraceae | 8 |
| Eucnide bartonioides | Zucc. | Loasaceae | 8 |
| Eucnide lobata | (Hook.) A.Gray | Loasaceae | 8 |
| Eucrypta micrantha | (Torr.) A.Heller | Hydrophyllaceae | 8 |
| Euonymus americanus | L. | Celastraceae | 8 |
| Euonymus atropurpureus | Jacq. | Celastraceae | 8 |
| Eupatorium altissimum | L. | Asteraceae | 8 |
| Eupatorium capillifolium | (Lam.) Small ex Porter & Britton | Asteraceae | 8 |
| Eupatorium compositifolium | Walter | Asteraceae | 8 |
| Eupatorium cuneifolium | Willd. | Asteraceae | 8 |
| Eupatorium hyssopifolium | L. | Asteraceae | 8 |
| Eupatorium leucolepis | Torr. & A.Gray | Asteraceae | 8 |
| Eupatorium mohrii | Greene | Asteraceae | 8 |
| Eupatorium perfoliatum | L. | Asteraceae | 8 |
| Eupatorium rotundifolium | L. | Asteraceae | 8 |
| Eupatorium semiserratum | DC. | Asteraceae | 8 |
| Eupatorium serotinum | Michx. | Asteraceae | 8 |
| Euphorbia abramsiana | L.C.Wheeler | Euphorbiaceae | 8 |
| Euphorbia acuta | Engelm. | Euphorbiaceae | 8 |
| Euphorbia albomarginata | Torr. & A.Gray | Euphorbiaceae | 8 |
| Euphorbia angusta | Engelm. | Euphorbiaceae | 8 |
| Euphorbia antisyphilitica | Zucc. | Euphorbiaceae | 8 |
| Euphorbia arizonica | Engelm. | Euphorbiaceae | 8 |
| Euphorbia astyla | Engelm. ex Boiss. | Euphorbiaceae | 8 |
| Euphorbia bicolor | Engelm. & Gray | Euphorbiaceae | 8 |
| Euphorbia bifurcata | Engelm. | Euphorbiaceae | 8 |
| Euphorbia bombensis | Jacq. | Euphorbiaceae | 8 |
| Euphorbia brachycera | Engelm. | Euphorbiaceae | 8 |
| Euphorbia capitellata | Engelm. | Euphorbiaceae | 8 |
| Euphorbia carunculata | Waterf. | Euphorbiaceae | 8 |
| Euphorbia chaetocalyx | (Boiss.) Tidestr. | Euphorbiaceae | 8 |
| Euphorbia cinerascens | Engelm. | Euphorbiaceae | 8 |
| Euphorbia commutata | Engelm. ex A.Gray | Euphorbiaceae | 8 |
| Euphorbia cordifolia | Elliott | Euphorbiaceae | 8 |
| Euphorbia corollata | L. | Euphorbiaceae | 8 |
| Euphorbia dentata | Michx. | Euphorbiaceae | 8 |
| Euphorbia discoidalis | Chapm. | Euphorbiaceae | 8 |
| Euphorbia eriantha | Benth. | Euphorbiaceae | 8 |
| Euphorbia exstipulata | Engelm. | Euphorbiaceae | 8 |
| Euphorbia fendleri | Torr. & A.Gray | Euphorbiaceae | 8 |
| Euphorbia geyeri | Engelm. | Euphorbiaceae | 8 |
| Euphorbia glyptosperma | Engelm. | Euphorbiaceae | 8 |
| Euphorbia golondrina | L.C.Wheeler | Euphorbiaceae | 8 |
| Euphorbia helleri | Millsp. | Euphorbiaceae | 8 |
| Euphorbia heterophylla | L. | Euphorbiaceae | 8 |
| Euphorbia hexagona | Nutt. ex Spreng. | Euphorbiaceae | 8 |
| Euphorbia hirta | L. | Euphorbiaceae | 8 |
| Euphorbia humistrata | Engelm. ex A.Gray | Euphorbiaceae | 8 |
| Euphorbia hypericifolia | L. | Euphorbiaceae | 8 |
| Euphorbia hyssopifolia | L. | Euphorbiaceae | 8 |
| Euphorbia indivisa | (Engelm.) Tidestr. | Euphorbiaceae | 8 |
| Euphorbia innocua | L.C.Wheeler | Euphorbiaceae | 8 |
| Euphorbia jejuna | M.C.Johnst. & Warnock | Euphorbiaceae | 8 |
| Euphorbia laredana | Millsp. | Euphorbiaceae | 8 |
| Euphorbia lata | Engelm. | Euphorbiaceae | 8 |
| Euphorbia longicruris | Scheele | Euphorbiaceae | 8 |
| Euphorbia maculata | L. | Euphorbiaceae | 8 |
| Euphorbia marginata | Pursh | Euphorbiaceae | 8 |
| Euphorbia micromera | Boiss. | Euphorbiaceae | 8 |
| Euphorbia missurica | Raf. | Euphorbiaceae | 8 |
| Euphorbia nutans | Lag. | Euphorbiaceae | 8 |
| Euphorbia parryi | Engelm. | Euphorbiaceae | 8 |
| Euphorbia peplidion | Engelm. | Euphorbiaceae | 8 |
| Euphorbia prostrata | Aiton | Euphorbiaceae | 8 |
| Euphorbia radians | Benth. | Euphorbiaceae | 8 |
| Euphorbia revoluta | Engelm. | Euphorbiaceae | 8 |
| Euphorbia roemeriana | Scheele | Euphorbiaceae | 8 |
| Euphorbia serpens | Kunth | Euphorbiaceae | 8 |
| Euphorbia serpillifolia | Pers. | Euphorbiaceae | 8 |
| Euphorbia serrula | Engelm. | Euphorbiaceae | 8 |
| Euphorbia setiloba | Engelm. | Euphorbiaceae | 8 |
| Euphorbia simulans | (L.C.Wheeler) Warnock & M.C.Johnst. | Euphorbiaceae | 8 |
| Euphorbia spathulata | Lam. | Euphorbiaceae | 8 |
| Euphorbia stictospora | Engelm. | Euphorbiaceae | 8 |
| Euphorbia tetrapora | Engelm. | Euphorbiaceae | 8 |
| Euphorbia triligulata | (L.C.Wheeler) A.M.Powell | Euphorbiaceae | 8 |
| Euphorbia villifera | Scheele | Euphorbiaceae | 8 |
| Euphrosyne dealbata | (A.Gray) Panero | Asteraceae | 8 |
| Euploca confertifolia | (Torr.) Feuillet & Halse | Heliotropiaceae | 8 |
| Euploca convolvulacea | Nutt. | Heliotropiaceae | 8 |
| Euploca greggii | (Torr.) Halse & Feuillet | Heliotropiaceae | 8 |
| Euploca procumbens | (Mill.) Diane & Hilger | Heliotropiaceae | 8 |
| Euploca racemosa | Rose & Standl. | Heliotropiaceae | 8 |
| Euploca tenella | (Torr.) Feuillet & Halse | Heliotropiaceae | 8 |
| Euploca torreyi | (I.M.Johnst.) Halse & Feuillet | Heliotropiaceae | 8 |
| Eurybia paludosa | (Aiton) G.L.Nesom | Asteraceae | 8 |
| Eurytaenia hinckleyi | Mathias & Constance | Apiaceae | 8 |
| Eustachys petraea | (Sw.) Desv. | Poaceae | 8 |
| Eustoma exaltatum | (L.) Salisb. ex G.Don | Gentianaceae | 8 |
| Eustoma russellianum | (Hook.) G.Don | Gentianaceae | 8 |
| Euthamia gymnospermoides | Greene | Asteraceae | 8 |
| Euthamia leptocephala | (Torr. & A.Gray) Greene ex Porter & Britton | Asteraceae | 8 |
| Eutrochium fistulosum | (Barratt) E.E.Lamont | Asteraceae | 8 |
| Evolvulus alsinoides | (L.) L. | Convolvulaceae | 8 |
| Evolvulus nuttallianus | Schult. | Convolvulaceae | 8 |
| Evolvulus sericeus | Sw. | Convolvulaceae | 8 |
| Eysenhardtia orthocarpa | (A.Gray) S.Watson | Fabaceae | 8 |
| Eysenhardtia texana | Scheele | Fabaceae | 8 |
| Facelis retusa | (Lam.) Sch.Bip. | Asteraceae | 8 |
| Fagus grandifolia | Ehrh. | Fagaceae | 8 |
| Fallopia scandens | (L.) Holub | Polygonaceae | 8 |
| Fallugia paradoxa | (D.Don ex Tilloch & Taylor) Endl. ex Torr. | Rosaceae | 8 |
| Fendlera rupicola | A.Gray | Hydrangeaceae | 8 |
| Fendlerella utahensis | (S.Watson) A.Heller | Hydrangeaceae | 8 |
| Ferocactus hamatacanthus | (Muehlenpf.) Britton & Rose | Cactaceae | 8 |
| Ferocactus uncinatus | (Galeotti ex Pfeiff.) Britton & Rose | Cactaceae | 8 |
| Ferocactus wislizeni | (Engelm.) Britton & Rose | Cactaceae | 8 |
| Festuca arizonica | Vasey | Poaceae | 8 |
| Festuca octoflora | Walter | Poaceae | 8 |
| Festuca paradoxa | Desv. | Poaceae | 8 |
| Festuca rubra | L. | Poaceae | 8 |
| Festuca subverticillata | (Pers.) E.B.Alexeev | Poaceae | 8 |
| Festuca versuta | Beal | Poaceae | 8 |
| Fimbristylis autumnalis | (L.) Roem. & Schult. | Cyperaceae | 8 |
| Fimbristylis caroliniana | (Lam.) Fernald | Cyperaceae | 8 |
| Fimbristylis cymosa | R.Br. | Cyperaceae | 8 |
| Fimbristylis dichotoma | (L.) Vahl | Cyperaceae | 8 |
| Fimbristylis littoralis | Gaudich. | Cyperaceae | 8 |
| Fimbristylis puberula | (Michx.) Vahl | Cyperaceae | 8 |
| Fimbristylis spadicea | (L.) Vahl | Cyperaceae | 8 |
| Fimbristylis vahlii | (Lam.) Link | Cyperaceae | 8 |
| Flaveria trinervia | (Spreng.) C.Mohr | Asteraceae | 8 |
| Fleischmannia incarnata | (Walter) R.M.King & H.Rob. | Asteraceae | 8 |
| Florestina tripteris | DC. | Asteraceae | 8 |
| Flourensia cernua | DC. | Asteraceae | 8 |
| Forestiera acuminata | (Michx.) Poir. | Oleaceae | 8 |
| Forestiera angustifolia | Torr. | Oleaceae | 8 |
| Forestiera ligustrina | (Michx.) Poir. | Oleaceae | 8 |
| Forestiera pubescens | Nutt. | Oleaceae | 8 |
| Forestiera reticulata | Torr. | Oleaceae | 8 |
| Fouquieria splendens | Engelm. | Fouquieriaceae | 8 |
| Fragaria vesca | L. | Rosaceae | 8 |
| Fragaria virginiana | Mill. | Rosaceae | 8 |
| Frangula caroliniana | (Walter) A.Gray | Rhamnaceae | 8 |
| Frankenia jamesii | Torr. ex A.Gray | Frankeniaceae | 8 |
| Frankenia johnstonii | Correll | Frankeniaceae | 8 |
| Frasera speciosa | Douglas ex Griseb. | Gentianaceae | 8 |
| Fraxinus albicans | Buckley | Oleaceae | 8 |
| Fraxinus americana | L. | Oleaceae | 8 |
| Fraxinus berlandieriana | A.DC. | Oleaceae | 8 |
| Fraxinus caroliniana | Mill. | Oleaceae | 8 |
| Fraxinus cuspidata | Torr. | Oleaceae | 8 |
| Fraxinus greggii | A.Gray | Oleaceae | 8 |
| Fraxinus papillosa | Lingelsh. | Oleaceae | 8 |
| Fraxinus pennsylvanica | Marshall | Oleaceae | 8 |
| Fraxinus velutina | Torr. | Oleaceae | 8 |
| Froelichia arizonica | Thornber ex Standl. | Amaranthaceae | 8 |
| Froelichia floridana | (Nutt.) Moq. | Amaranthaceae | 8 |
| Froelichia gracilis | (Hook.) Moq. | Amaranthaceae | 8 |
| Fuirena breviseta | (Coville) Coville | Cyperaceae | 8 |
| Fuirena scirpoidea | Michx. | Cyperaceae | 8 |
| Fuirena simplex | Vahl | Cyperaceae | 8 |
| Fuirena squarrosa | Michx. | Cyperaceae | 8 |
| Funastrum angustifolium | (Pers.) Liede & Meve | Apocynaceae | 8 |
| Funastrum clausum | (Jacq.) Schltr. | Apocynaceae | 8 |
| Funastrum crispum | (Benth.) Schltr. | Apocynaceae | 8 |
| Funastrum cynanchoides | (Decne.) Schltr. | Apocynaceae | 8 |
| Funastrum heterophyllum | (Engelm. ex Torr.) Standl. | Apocynaceae | 8 |
| Funastrum torreyi | (A.Gray) Schltr. | Apocynaceae | 8 |
| Gaga kaulfussii | (Kunze) Fay W.Li & Windham | Pteridaceae | 8 |
| Gaillardia aestivalis | (Walter) H.Rock | Asteraceae | 8 |
| Gaillardia multiceps | Greene | Asteraceae | 8 |
| Gaillardia pinnatifida | Torr. | Asteraceae | 8 |
| Gaillardia pulchella | Foug. | Asteraceae | 8 |
| Gaillardia suavis | (A.Gray & Engelm.) Britton & Rusby | Asteraceae | 8 |
| Galactia canescens | Benth. | Fabaceae | 8 |
| Galactia erecta | (Walter) Vail | Fabaceae | 8 |
| Galactia regularis | (L.) Britton, Sterns & Poggenb. | Fabaceae | 8 |
| Galactia texana | (Scheele) A.Gray | Fabaceae | 8 |
| Galactia volubilis | (L.) Britton | Fabaceae | 8 |
| Galactia wrightii | A.Gray | Fabaceae | 8 |
| Galinsoga parviflora | Cav. | Asteraceae | 8 |
| Galium mexicanum | Kunth | Rubiaceae | 8 |
| Galium obtusum | Bigelow | Rubiaceae | 8 |
| Galium pilosum | Aiton | Rubiaceae | 8 |
| Galium proliferum | A.Gray | Rubiaceae | 8 |
| Galium texense | A.Gray | Rubiaceae | 8 |
| Galium trifidum | L. | Rubiaceae | 8 |
| Galium triflorum | Michx. | Rubiaceae | 8 |
| Galium uniflorum | Michx. | Rubiaceae | 8 |
| Galium virgatum | Nutt. | Rubiaceae | 8 |
| Galium wrightii | A.Gray | Rubiaceae | 8 |
| Galphimia angustifolia | Benth. | Malpighiaceae | 8 |
| Gamochaeta argyrinea | G.L.Nesom | Asteraceae | 8 |
| Gamochaeta calviceps | (Fernald) Cabrera | Asteraceae | 8 |
| Gamochaeta pensylvanica | (Willd.) Cabrera | Asteraceae | 8 |
| Gamochaeta purpurea | (L.) Cabrera | Asteraceae | 8 |
| Gamochaeta stagnalis | (I.M.Johnst.) Anderb. | Asteraceae | 8 |
| Garrya goldmanii | Wooton & Standl. | Garryaceae | 8 |
| Garrya lindheimeri | Torr. | Garryaceae | 8 |
| Garrya wrightii | Torr. | Garryaceae | 8 |
| Gelsemium sempervirens | (L.) J.St.-Hil. | Gelsemiaceae | 8 |
| Genistidium dumosum | I.M.Johnst. | Fabaceae | 8 |
| Gentiana affinis | Griseb. | Gentianaceae | 8 |
| Gentiana saponaria | L. | Gentianaceae | 8 |
| Geocarpon minimum | Mack. | Caryophyllaceae | 8 |
| Geranium caespitosum | E.James | Geraniaceae | 8 |
| Geranium carolinianum | L. | Geraniaceae | 8 |
| Geranium seemannii | Peyr. | Geraniaceae | 8 |
| Geranium texanum | (Trel.) A.Heller | Geraniaceae | 8 |
| Geum canadense | Jacq. | Rosaceae | 8 |
| Gilia lyndana | Allred | Polemoniaceae | 8 |
| Gilia mexicana | A.D.Grant & V.E.Grant | Polemoniaceae | 8 |
| Giliastrum acerosum | (A.Gray) Rydb. | Polemoniaceae | 8 |
| Giliastrum incisum | (Benth.) J.M.Porter | Polemoniaceae | 8 |
| Giliastrum rigidulum | Rydb. | Polemoniaceae | 8 |
| Giliastrum stewartii | (I.M.Johnst.) J.M.Porter | Polemoniaceae | 8 |
| Gillenia stipulata | (Muhl. ex Willd.) Nutt. | Rosaceae | 8 |
| Gleditsia aquatica | Marshall | Fabaceae | 8 |
| Gleditsia triacanthos | L. | Fabaceae | 8 |
| Glinus radiatus | (Ruiz & Pav.) Rohrb. | Molluginaceae | 8 |
| Glossopetalon spinescens | A.Gray | Crossosomataceae | 8 |
| Glyceria septentrionalis | Hitchc. | Poaceae | 8 |
| Glyceria striata | (Lam.) Hitchc. | Poaceae | 8 |
| Glycyrrhiza lepidota | Pursh | Fabaceae | 8 |
| Gomphrena caespitosa | Torr. | Amaranthaceae | 8 |
| Gomphrena lanuparonychioides | T. Ortuño & Borsch | Amaranthaceae | 8 |
| Gomphrena serrata | L. | Amaranthaceae | 8 |
| Gomphrena vermicularis | L. | Amaranthaceae | 8 |
| Gonolobus suberosus | (L.) R.Br. | Apocynaceae | 8 |
| Gratiola brevifolia | Raf. | Plantaginaceae | 8 |
| Gratiola neglecta | Torr. | Plantaginaceae | 8 |
| Gratiola pilosa | Michx. | Plantaginaceae | 8 |
| Gratiola quartermaniae | D.Estes | Plantaginaceae | 8 |
| Gratiola torreyi | Small | Plantaginaceae | 8 |
| Gratiola virginiana | L. | Plantaginaceae | 8 |
| Grindelia adenodonta | (Steyerm.) G.L.Nesom | Asteraceae | 8 |
| Grindelia ciliata | (Nutt.) Spreng. | Asteraceae | 8 |
| Grindelia lanceolata | Nutt. | Asteraceae | 8 |
| Grindelia scabra | Greene | Asteraceae | 8 |
| Grindelia squarrosa | (Pursh) Dunal | Asteraceae | 8 |
| Grusonia aggeria | (Ralston & Hilsenb.) E.F.Anderson | Cactaceae | 8 |
| Grusonia emoryi | (Engelm.) Pinkava | Cactaceae | 8 |
| Grusonia grahamii | (Engelm.) H.Rob. | Cactaceae | 8 |
| Grusonia schottii | (Engelm.) H.Rob. | Cactaceae | 8 |
| Guilleminea densa | (Humb. & Bonpl. ex Schult.) Moq. | Amaranthaceae | 8 |
| Gutierrezia dracunculoides | (DC.) O.Hoffm. | Asteraceae | 8 |
| Gutierrezia microcephala | (DC.) A.Gray | Asteraceae | 8 |
| Gutierrezia sarothrae | (Pursh) Britton & Rusby | Asteraceae | 8 |
| Gutierrezia sphaerocephala | A.Gray | Asteraceae | 8 |
| Gymnocladus dioicus | (L.) K.Koch | Fabaceae | 8 |
| Gymnopogon ambiguus | (Michx.) Britton, Sterns & Poggenb. | Poaceae | 8 |
| Gymnopogon brevifolius | Trin. | Poaceae | 8 |
| Gymnosperma glutinosum | (Spreng.) Less. | Asteraceae | 8 |
| Habenaria quinqueseta | (Michx.) Eaton | Orchidaceae | 8 |
| Habenaria repens | Nutt. | Orchidaceae | 8 |
| Habranthus longifolius | (Hemsl.) Flagg, G.Lom.Sm. & Meerow | Amaryllidaceae | 8 |
| Hackelia floribunda | (Lehm.) I.M.Johnst. | Boraginaceae | 8 |
| Hackelia virginiana | (L.) I.M.Johnst. | Boraginaceae | 8 |
| Halerpestes cymbalaria | Greene | Ranunculaceae | 8 |
| Halesia diptera | J.Ellis | Styracaceae | 8 |
| Halophila engelmannii | Asch. | Hydrocharitaceae | 8 |
| Hamamelis virginiana | L. | Hamamelidaceae | 8 |
| Haplophyton crooksii | (L.D.Benson) L.D.Benson | Apocynaceae | 8 |
| Havardia pallens | (Benth.) Britton & Rose | Fabaceae | 8 |
| Hebecarpa barbeyana | (Chodat) J.R.Abbott | Polygalaceae | 8 |
| Hebecarpa macradenia | (A.Gray) J.R.Abbott | Polygalaceae | 8 |
| Hebecarpa obscura | (Benth.) J.R.Abbott | Polygalaceae | 8 |
| Hebecarpa ovatifolia | (A.Gray) J.R.Abbott | Polygalaceae | 8 |
| Hechtia glomerata | Zucc. | Bromeliaceae | 8 |
| Hechtia texensis | S.Watson | Bromeliaceae | 8 |
| Hedeoma acinoides | Scheele | Lamiaceae | 8 |
| Hedeoma costata | A.Gray | Lamiaceae | 8 |
| Hedeoma drummondii | Benth. | Lamiaceae | 8 |
| Hedeoma hispida | Pursh | Lamiaceae | 8 |
| Hedeoma nana | (Torr.) Briq. | Lamiaceae | 8 |
| Hedeoma plicata | Torr. | Lamiaceae | 8 |
| Hedeoma reverchonii | (A.Gray) A.Gray | Lamiaceae | 8 |
| Hedosyne ambrosiifolia | (A.Gray) Strother | Asteraceae | 8 |
| Hedysarum boreale | Nutt. | Fabaceae | 8 |
| Heimia salicifolia | Link | Lythraceae | 8 |
| Helenium amarum | (Raf.) H.Rock | Asteraceae | 8 |
| Helenium autumnale | L. | Asteraceae | 8 |
| Helenium drummondii | H.Rock | Asteraceae | 8 |
| Helenium elegans | DC. | Asteraceae | 8 |
| Helenium flexuosum | Raf. | Asteraceae | 8 |
| Helenium microcephalum | DC. | Asteraceae | 8 |
| Helianthus angustifolius | L. | Asteraceae | 8 |
| Helianthus argophyllus | Torr. & A.Gray | Asteraceae | 8 |
| Helianthus ciliaris | DC. | Asteraceae | 8 |
| Helianthus debilis | Nutt. | Asteraceae | 8 |
| Helianthus grosseserratus | M.Martens | Asteraceae | 8 |
| Helianthus heterophyllus | Nutt. | Asteraceae | 8 |
| Helianthus hirsutus | Raf. | Asteraceae | 8 |
| Helianthus laciniatus | A.Gray | Asteraceae | 8 |
| Helianthus maximiliani | Schrad. | Asteraceae | 8 |
| Helianthus mollis | Lam. | Asteraceae | 8 |
| Helianthus occidentalis | Riddell | Asteraceae | 8 |
| Helianthus pauciflorus | Nutt. | Asteraceae | 8 |
| Helianthus petiolaris | Nutt. | Asteraceae | 8 |
| Helianthus praecox | Engelm. & A.Gray | Asteraceae | 8 |
| Helianthus salicifolius | A.Dietr. | Asteraceae | 8 |
| Helianthus simulans | E.Watson | Asteraceae | 8 |
| Helianthus strumosus | L. | Asteraceae | 8 |
| Helianthus tuberosus | L. | Asteraceae | 8 |
| Helietta parvifolia | Benth. | Rutaceae | 8 |
| Heliomeris longifolia | Cockerell | Asteraceae | 8 |
| Heliomeris multiflora | Nutt. | Asteraceae | 8 |
| Heliopsis gracilis | Nutt. | Asteraceae | 8 |
| Heliopsis helianthoides | Sweet | Asteraceae | 8 |
| Heliopsis parvifolia | A.Gray | Asteraceae | 8 |
| Heliotropium angiospermum | Murray | Heliotropiaceae | 8 |
| Heliotropium curassavicum | L. | Heliotropiaceae | 8 |
| Heliotropium verdcourtii | Craven | Heliotropiaceae | 8 |
| Herissantia crispa | (L.) Brizicky | Malvaceae | 8 |
| Hermannia texana | A.Gray | Malvaceae | 8 |
| Hesperaloe engelmannii | Krauskopf ex Baker | Asparagaceae | 8 |
| Hesperaloe funifera | (K.Koch) Trel. | Asparagaceae | 8 |
| Hesperaloe parviflora | (Torr.) J.M.Coult. | Asparagaceae | 8 |
| Hesperidanthus linearifolius | (A.Gray) Rydb. | Brassicaceae | 8 |
| Hesperocyparis arizonica | (Greene) Bartel | Cupressaceae | 8 |
| Hesperostipa comata | (Trin. & Rupr.) Barkworth | Poaceae | 8 |
| Hesperostipa neomexicana | (Thurb.) Barkworth | Poaceae | 8 |
| Heteranthera dubia | (Jacq.) MacMill. | Pontederiaceae | 8 |
| Heteranthera limosa | (Sw.) Willd. | Pontederiaceae | 8 |
| Heteranthera reniformis | Ruiz & Pav. | Pontederiaceae | 8 |
| Heteropogon contortus | (L.) P.Beauv. ex Roem. & Schult. | Poaceae | 8 |
| Heteropogon melanocarpus | (Elliott) Benth. | Poaceae | 8 |
| Heterosperma pinnatum | Cav. | Asteraceae | 8 |
| Heterotheca canescens | (DC.) Shinners | Asteraceae | 8 |
| Heterotheca fulcrata | (Greene) Shinners | Asteraceae | 8 |
| Heterotheca stenophylla | (A.Gray) Shinners | Asteraceae | 8 |
| Heterotheca subaxillaris | (Lam.) Britton & Rusby | Asteraceae | 8 |
| Heterotheca viscida | (A.Gray) V.L.Harms | Asteraceae | 8 |
| Heterotheca zionensis | Semple | Asteraceae | 8 |
| Heuchera rubescens | Torr. | Saxifragaceae | 8 |
| Hexasepalum teres | (Walter) J.H.Kirkbr. | Rubiaceae | 8 |
| Hibiscus coulteri | Harv. ex A.Gray | Malvaceae | 8 |
| Hibiscus denudatus | Benth. | Malvaceae | 8 |
| Hibiscus martianus | Zucc. | Malvaceae | 8 |
| Hibiscus striatus | Cav. | Malvaceae | 8 |
| Hieracium fendleri | Sch.Bip. | Asteraceae | 8 |
| Hieracium gronovii | L. | Asteraceae | 8 |
| Hieracium longipilum | Torr. ex Hook. | Asteraceae | 8 |
| Hilaria belangeri | (Steud.) Nash | Poaceae | 8 |
| Hilaria jamesii | (Torr.) Benth. | Poaceae | 8 |
| Hilaria mutica | (Buckley) Benth. | Poaceae | 8 |
| Hoffmannseggia drepanocarpa | A.Gray | Fabaceae | 8 |
| Hoffmannseggia glauca | (Ortega) Eifert | Fabaceae | 8 |
| Hoffmannseggia oxycarpa | Benth. | Fabaceae | 8 |
| Hoffmannseggia tenella | Tharp & L.O.Williams | Fabaceae | 8 |
| Holodiscus discolor | (Pursh) Maxim. | Rosaceae | 8 |
| Homalocephala texensis | (Hopffer) Britton & Rose | Cactaceae | 8 |
| Hopia obtusa | (Kunth) Zuloaga & Morrone | Poaceae | 8 |
| Hordeum brachyantherum | Nevski | Poaceae | 8 |
| Hordeum jubatum | L. | Poaceae | 8 |
| Hottonia inflata | Elliott | Primulaceae | 8 |
| Houstonia acerosa | (A.Gray) Benth. & Hook.f. | Rubiaceae | 8 |
| Houstonia humifusa | (Engelm. ex A.Gray) A.Gray | Rubiaceae | 8 |
| Houstonia longifolia | Gaertn. | Rubiaceae | 8 |
| Houstonia micrantha | (Shinners) Terrell | Rubiaceae | 8 |
| Houstonia purpurea | L. | Rubiaceae | 8 |
| Houstonia pusilla | Schoepf | Rubiaceae | 8 |
| Houstonia rosea | (Raf.) Terrell | Rubiaceae | 8 |
| Houstonia rubra | Cav. | Rubiaceae | 8 |
| Houstonia wrightii | A.Gray | Rubiaceae | 8 |
| Humulus neomexicanus | (A.Nelson & Cockerell) Rydb. | Cannabaceae | 8 |
| Hunnemannia fumariifolia | Sweet | Papaveraceae | 8 |
| Hunzikeria texana | (Torr.) D'Arcy | Solanaceae | 8 |
| Hydrocharis spongia | Bosc | Hydrocharitaceae | 8 |
| Hydrocotyle bonariensis | Comm. ex Lam. | Araliaceae | 8 |
| Hydrocotyle ranunculoides | L.f. | Araliaceae | 8 |
| Hydrocotyle umbellata | L. | Araliaceae | 8 |
| Hydrocotyle verticillata | Thunb. | Araliaceae | 8 |
| Hydrogalium claytonii | (Michx.) Kadereit & Schneew. | Rubiaceae | 8 |
| Hydrolea ovata | Nutt. | Hydroleaceae | 8 |
| Hydrolea spinosa | L. | Hydroleaceae | 8 |
| Hydrolea uniflora | Raf. | Hydroleaceae | 8 |
| Hylodesmum glutinosum | (Muhl. ex Willd.) H.Ohashi & R.R.Mill | Fabaceae | 8 |
| Hylodesmum nudiflorum | (L.) H.Ohashi & R.R.Mill | Fabaceae | 8 |
| Hylodesmum pauciflorum | (Nutt.) H.Ohashi & R.R.Mill | Fabaceae | 8 |
| Hymenocallis liriosme | (Raf.) Shinners | Amaryllidaceae | 8 |
| Hymenocallis occidentalis | (Leconte) Kunth | Amaryllidaceae | 8 |
| Hymenopappus artemisiifolius | DC. | Asteraceae | 8 |
| Hymenopappus biennis | B.L.Turner | Asteraceae | 8 |
| Hymenopappus carrizoanus | B.L.Turner | Asteraceae | 8 |
| Hymenopappus filifolius | Hook. | Asteraceae | 8 |
| Hymenopappus flavescens | A.Gray | Asteraceae | 8 |
| Hymenopappus scabiosaeus | L'Hér. | Asteraceae | 8 |
| Hymenopappus tenuifolius | Pursh | Asteraceae | 8 |
| Hymenothrix dissecta | (A.Gray) B.G.Baldwin | Asteraceae | 8 |
| Hymenothrix pedata | (A.Gray) B.G.Baldwin | Asteraceae | 8 |
| Hymenothrix wislizeni | A.Gray | Asteraceae | 8 |
| Hymenothrix wrightii | A.Gray | Asteraceae | 8 |
| Hymenoxys odorata | DC. | Asteraceae | 8 |
| Hymenoxys perpygmaea | W.C.Holmes, Singhurst & Mink | Asteraceae | 8 |
| Hymenoxys richardsonii | Cockerell | Asteraceae | 8 |
| Hypericum cistifolium | Lam. | Hypericaceae | 8 |
| Hypericum crux-andreae | (L.) Crantz | Hypericaceae | 8 |
| Hypericum drummondii | (Grev. & Hook.) Torr. & A.Gray | Hypericaceae | 8 |
| Hypericum frondosum | Michx. | Hypericaceae | 8 |
| Hypericum galioides | Lam. | Hypericaceae | 8 |
| Hypericum gentianoides | (L.) Britton, Sterns & Poggenb. | Hypericaceae | 8 |
| Hypericum gymnanthum | Engelm. & A.Gray | Hypericaceae | 8 |
| Hypericum hypericoides | (L.) Crantz | Hypericaceae | 8 |
| Hypericum mutilum | L. | Hypericaceae | 8 |
| Hypericum prolificum | L. | Hypericaceae | 8 |
| Hypericum pseudomaculatum | Bush | Hypericaceae | 8 |
| Hypericum punctatum | Lam. | Hypericaceae | 8 |
| Hypericum setosum | L. | Hypericaceae | 8 |
| Hypericum sphaerocarpum | Michx. | Hypericaceae | 8 |
| Hypericum tubulosum | Walter | Hypericaceae | 8 |
| Hypericum virginicum | L. | Hypericaceae | 8 |
| Hypericum walteri | J.F.Gmel. | Hypericaceae | 8 |
| Hypopitys monotropa | Crantz | Ericaceae | 8 |
| Hypoxis curtissii | Rose | Hypoxidaceae | 8 |
| Hypoxis hirsuta | (L.) Coville | Hypoxidaceae | 8 |
| Hypoxis wrightii | (Baker) Brackett | Hypoxidaceae | 8 |
| Hyptis alata | (Raf.) Shinners | Lamiaceae | 8 |
| Ibervillea lindheimeri | (A.Gray) Greene | Cucurbitaceae | 8 |
| Ibervillea tenuisecta | (A.Gray) Small | Cucurbitaceae | 8 |
| Ilex ambigua | (Michx.) Torr. | Aquifoliaceae | 8 |
| Ilex cassine | L. | Aquifoliaceae | 8 |
| Ilex coriacea | (Pursh) Chapm. | Aquifoliaceae | 8 |
| Ilex decidua | Walter | Aquifoliaceae | 8 |
| Ilex glabra | (L.) A.Gray | Aquifoliaceae | 8 |
| Ilex longipes | Chapm. ex Trel. | Aquifoliaceae | 8 |
| Ilex opaca | Aiton | Aquifoliaceae | 8 |
| Ilex verticillata | (L.) A.Gray | Aquifoliaceae | 8 |
| Ilex vomitoria | Aiton | Aquifoliaceae | 8 |
| Impatiens capensis | Meerb. | Balsaminaceae | 8 |
| Indigofera lindheimeriana | Scheele | Fabaceae | 8 |
| Indigofera miniata | Ortega | Fabaceae | 8 |
| Indigofera suffruticosa | Mill. | Fabaceae | 8 |
| Iodanthus pinnatifidus | Steud. | Brassicaceae | 8 |
| Ionactis linariifolia | (L.) Greene | Asteraceae | 8 |
| Ipomoea aristolochiifolia | G.Don | Convolvulaceae | 8 |
| Ipomoea barbatisepala | A.Gray | Convolvulaceae | 8 |
| Ipomoea capillacea | (Kunth) G.Don | Convolvulaceae | 8 |
| Ipomoea cardiophylla | A.Gray | Convolvulaceae | 8 |
| Ipomoea coccinea | L. | Convolvulaceae | 8 |
| Ipomoea cordatotriloba | Dennst. | Convolvulaceae | 8 |
| Ipomoea costellata | Torr. | Convolvulaceae | 8 |
| Ipomoea cristulata | Hallier f. | Convolvulaceae | 8 |
| Ipomoea dumetorum | Willd. | Convolvulaceae | 8 |
| Ipomoea hederifolia | L. | Convolvulaceae | 8 |
| Ipomoea imperati | (Vahl) Griseb. | Convolvulaceae | 8 |
| Ipomoea indica | (Burm.) Merr. | Convolvulaceae | 8 |
| Ipomoea lacunosa | L. | Convolvulaceae | 8 |
| Ipomoea leptophylla | Torr. | Convolvulaceae | 8 |
| Ipomoea lindheimeri | A.Gray | Convolvulaceae | 8 |
| Ipomoea pandurata | G.Mey. | Convolvulaceae | 8 |
| Ipomoea pes-caprae | (L.) R.Br. | Convolvulaceae | 8 |
| Ipomoea plummerae | A.Gray | Convolvulaceae | 8 |
| Ipomoea pubescens | Lam. | Convolvulaceae | 8 |
| Ipomoea sagittata | Poir. | Convolvulaceae | 8 |
| Ipomoea violacea | L. | Convolvulaceae | 8 |
| Ipomopsis aggregata | (Pursh) V.E.Grant | Polemoniaceae | 8 |
| Ipomopsis laxiflora | (J.M.Coult.) V.E.Grant | Polemoniaceae | 8 |
| Ipomopsis longiflora | (Torr.) V.E.Grant | Polemoniaceae | 8 |
| Ipomopsis polycladon | (Torr.) V.E.Grant | Polemoniaceae | 8 |
| Ipomopsis pumila | (Nutt.) V.E.Grant | Polemoniaceae | 8 |
| Ipomopsis rubra | (L.) Wherry | Polemoniaceae | 8 |
| Ipomopsis thurberi | (A.Gray) V.E.Grant | Polemoniaceae | 8 |
| Iresine diffusa | Humb. & Bonpl. ex Willd. | Amaranthaceae | 8 |
| Iresine heterophylla | Standl. | Amaranthaceae | 8 |
| Iresine palmeri | (S.Watson) Standl. | Amaranthaceae | 8 |
| Iresine rhizomatosa | Standl. | Amaranthaceae | 8 |
| Iris virginica | L. | Iridaceae | 8 |
| Isocarpha oppositifolia | (L.) Cass. | Asteraceae | 8 |
| Isocoma coronopifolia | Greene | Asteraceae | 8 |
| Isocoma drummondii | Greene | Asteraceae | 8 |
| Isocoma pluriflora | (Torr. & A.Gray) Greene | Asteraceae | 8 |
| Isoetes butleri | Engelm. | Isoetaceae | 8 |
| Isoetes lithophila | N.Pfeiff. | Isoetaceae | 8 |
| Isolepis carinata | Hook. & Arn. ex Torr. | Cyperaceae | 8 |
| Isolepis cernua | (Vahl) Roem. & Schult. | Cyperaceae | 8 |
| Isotria verticillata | (Muhl. ex Willd.) Raf. | Orchidaceae | 8 |
| Itea virginica | L. | Iteaceae | 8 |
| Iva angustifolia | Nutt. ex DC. | Asteraceae | 8 |
| Iva annua | L. | Asteraceae | 8 |
| Iva axillaris | Pursh | Asteraceae | 8 |
| Iva frutescens | L. | Asteraceae | 8 |
| Iva imbricata | Walter | Asteraceae | 8 |
| Jacquemontia tamnifolia | (L.) Griseb. | Convolvulaceae | 8 |
| Jatropha cathartica | Terán & Berland. | Euphorbiaceae | 8 |
| Jatropha dioica | Sessé | Euphorbiaceae | 8 |
| Jefea brevifolia | (A.Gray) Strother | Asteraceae | 8 |
| Johnstonella albida | (Kunth) M.E.Mabry & M.G.Simpson | Boraginaceae | 8 |
| Johnstonella angustifolia | (Torr.) Hasenstab & M.G.Simpson | Boraginaceae | 8 |
| Johnstonella mexicana | (Brandegee) M.E.Mabry & M.G.Simpson | Boraginaceae | 8 |
| Johnstonella pusilla | (Torr. & A.Gray) Hasenstab & M.G.Simpson | Boraginaceae | 8 |
| Juglans major | (Torr.) A.Heller | Juglandaceae | 8 |
| Juglans microcarpa | Berland. | Juglandaceae | 8 |
| Juglans nigra | L. | Juglandaceae | 8 |
| Juncus acuminatus | Michx. | Juncaceae | 8 |
| Juncus anthelatus | (Wiegand) R.E.Brooks & Whittem. | Juncaceae | 8 |
| Juncus balticus | Willd. | Juncaceae | 8 |
| Juncus biflorus | Elliott | Juncaceae | 8 |
| Juncus brachycarpus | Engelm. | Juncaceae | 8 |
| Juncus bufonius | L. | Juncaceae | 8 |
| Juncus coriaceus | Mack. | Juncaceae | 8 |
| Juncus dichotomus | Elliott | Juncaceae | 8 |
| Juncus diffusissimus | Buckley | Juncaceae | 8 |
| Juncus dudleyi | Wiegand | Juncaceae | 8 |
| Juncus effusus | L. | Juncaceae | 8 |
| Juncus filipendulus | Buckley | Juncaceae | 8 |
| Juncus interior | Wiegand | Juncaceae | 8 |
| Juncus marginatus | Rostk. | Juncaceae | 8 |
| Juncus megacephalus | M.A.Curtis | Juncaceae | 8 |
| Juncus nodosus | L. | Juncaceae | 8 |
| Juncus polycephalus | Michx. | Juncaceae | 8 |
| Juncus repens | Michx. | Juncaceae | 8 |
| Juncus roemerianus | Scheele | Juncaceae | 8 |
| Juncus scirpoides | Lam. | Juncaceae | 8 |
| Juncus tenuis | Willd. | Juncaceae | 8 |
| Juncus torreyi | Coville | Juncaceae | 8 |
| Juncus trigonocarpus | Steud. | Juncaceae | 8 |
| Juncus validus | Coville | Juncaceae | 8 |
| Juniperus arizonica | (R.P.Adams) R.P.Adams | Cupressaceae | 8 |
| Juniperus ashei | J.Buchholz | Cupressaceae | 8 |
| Juniperus coahuilensis | (Martínez) Gaussen ex R.P.Adams | Cupressaceae | 8 |
| Juniperus deppeana | Steud. | Cupressaceae | 8 |
| Juniperus flaccida | Schltdl. | Cupressaceae | 8 |
| Juniperus monosperma | (Engelm.) Sarg. | Cupressaceae | 8 |
| Juniperus pinchotii | Sudw. | Cupressaceae | 8 |
| Juniperus virginiana | L. | Cupressaceae | 8 |
| Justicia lanceolata | (Chapm.) Small | Acanthaceae | 8 |
| Justicia longii | Hilsenb. | Acanthaceae | 8 |
| Justicia pacifica | (Oerst.) Hemsl. | Acanthaceae | 8 |
| Justicia pilosella | (Nees) Hilsenb. | Acanthaceae | 8 |
| Kallstroemia californica | (S.Watson) Vail | Zygophyllaceae | 8 |
| Kallstroemia grandiflora | Torr. ex A.Gray | Zygophyllaceae | 8 |
| Kallstroemia maxima | (L.) Hook. & Arn. | Zygophyllaceae | 8 |
| Kallstroemia parviflora | Norton | Zygophyllaceae | 8 |
| Karwinskia humboldtiana | (Schult.) Zucc. | Rhamnaceae | 8 |
| Kellochloa brachyantha | (Steud.) Lizarazu, Nicola & Scataglini | Poaceae | 8 |
| Kellochloa verrucosa | (Muhl.) Lizarazu, Nicola & Scataglini | Poaceae | 8 |
| Koeberlinia spinosa | Zucc. | Koeberliniaceae | 8 |
| Koeleria macrantha | (Ledeb.) Schult. | Poaceae | 8 |
| Koeleria spicata | (L.) Barberá, Quintanar, Soreng & P.M.Peterson | Poaceae | 8 |
| Kosteletzkya depressa | (L.) O.J.Blanch., Fryxell & D.M.Bates | Malvaceae | 8 |
| Kosteletzkya pentacarpos | (L.) Ledeb. | Malvaceae | 8 |
| Krameria bicolor | S.Watson | Krameriaceae | 8 |
| Krameria erecta | Willd. | Krameriaceae | 8 |
| Krameria lanceolata | Torr. | Krameriaceae | 8 |
| Krameria ramosissima | S.Watson | Krameriaceae | 8 |
| Krascheninnikovia ceratoides | (L.) Gueldenst. | Chenopodiaceae | 8 |
| Krigia cespitosa | (Raf.) K.L.Chambers | Asteraceae | 8 |
| Krigia dandelion | (L.) Nutt. | Asteraceae | 8 |
| Krigia occidentalis | Nutt. | Asteraceae | 8 |
| Krigia virginica | (L.) Willd. | Asteraceae | 8 |
| Krigia wrightii | (A.Gray) K.L.Chambers ex K.J.Kim | Asteraceae | 8 |
| Lackeya multiflora | (Torr. & A.Gray) Fortunato, L.P.Queiroz & G.P.Lewis | Fabaceae | 8 |
| Lactuca canadensis | L. | Asteraceae | 8 |
| Lactuca floridana | (L.) Gaertn. | Asteraceae | 8 |
| Lactuca graminifolia | Michx. | Asteraceae | 8 |
| Lactuca hirsuta | Muhl. ex Nutt. | Asteraceae | 8 |
| Lactuca ludoviciana | (Nutt.) Riddell | Asteraceae | 8 |
| Lactuca oblongifolia | Nutt. | Asteraceae | 8 |
| Ladeania lanceolata | (Pursh) Reveal & A.N.Egan | Fabaceae | 8 |
| Laennecia coulteri | (A.Gray) G.L.Nesom | Asteraceae | 8 |
| Laennecia filaginoides | DC. | Asteraceae | 8 |
| Laennecia schiedeana | (Less.) G.L.Nesom | Asteraceae | 8 |
| Laennecia sophiifolia | (Kunth) G.L.Nesom | Asteraceae | 8 |
| Laguncularia racemosa | (L.) C.F.Gaertn. | Combretaceae | 8 |
| Lantana achyranthifolia | Desf. | Verbenaceae | 8 |
| Lantana canescens | Kunth | Verbenaceae | 8 |
| Lantana urticoides | Hayek | Verbenaceae | 8 |
| Lantana velutina | M.Martens & Galeotti | Verbenaceae | 8 |
| Lappula occidentalis | (S.Watson) Greene | Boraginaceae | 8 |
| Larrea tridentata | (DC.) Coville | Zygophyllaceae | 8 |
| Lathyrus decaphyllus | Pursh | Fabaceae | 8 |
| Lathyrus eucosmus | Butters & H.St.John | Fabaceae | 8 |
| Lathyrus graminifolius | (S.Watson) T.G.White | Fabaceae | 8 |
| Lathyrus lanszwertii | Kellogg | Fabaceae | 8 |
| Lathyrus pusillus | Elliott | Fabaceae | 8 |
| Lathyrus venosus | Muhl. ex Willd. | Fabaceae | 8 |
| Leavenworthia texana | Mahler | Brassicaceae | 8 |
| Lechea minor | L. | Cistaceae | 8 |
| Lechea mucronata | Raf. | Cistaceae | 8 |
| Lechea san-sabeana | (Buckley) Hodgdon | Cistaceae | 8 |
| Lechea tenuifolia | Michx. | Cistaceae | 8 |
| Leersia hexandra | Sw. | Poaceae | 8 |
| Leersia lenticularis | Michx. | Poaceae | 8 |
| Leersia monandra | Sw. | Poaceae | 8 |
| Leersia oryzoides | (L.) Sw. | Poaceae | 8 |
| Leersia virginica | Willd. | Poaceae | 8 |
| Lemna aequinoctialis | Welw. | Araceae | 8 |
| Lemna gibba | L. | Araceae | 8 |
| Lemna minor | L. | Araceae | 8 |
| Lemna minuta | Kunth | Araceae | 8 |
| Lemna trisulca | L. | Araceae | 8 |
| Lemna turionifera | Landolt | Araceae | 8 |
| Lenophyllum texanum | (Donn.Sm.) Rose | Crassulaceae | 8 |
| Lepidium alyssoides | A.Gray | Brassicaceae | 8 |
| Lepidium austrinum | Small | Brassicaceae | 8 |
| Lepidium densiflorum | Schrad. | Brassicaceae | 8 |
| Lepidium lasiocarpum | Nutt. | Brassicaceae | 8 |
| Lepidium oblongum | Small | Brassicaceae | 8 |
| Lepidium thurberi | Wooton | Brassicaceae | 8 |
| Lepidium virginicum | L. | Brassicaceae | 8 |
| Lepidospartum burgessii | B.L.Turner | Asteraceae | 8 |
| Leptochloa crinita | (Lag.) P.M.Peterson & N.Snow | Poaceae | 8 |
| Leptochloa nealleyi | Vasey | Poaceae | 8 |
| Leptochloa panicea | (Retz.) Ohwi | Poaceae | 8 |
| Leptochloa panicoides | (J.Presl) Hitchc. | Poaceae | 8 |
| Leptochloa pluriflora | (E.Fourn.) P.M.Peterson & N.Snow | Poaceae | 8 |
| Lepuropetalon spathulatum | Elliott | Celastraceae | 8 |
| Lespedeza frutescens | (L.) Hornem. | Fabaceae | 8 |
| Lespedeza hirta | (L.) Hornem. | Fabaceae | 8 |
| Lespedeza procumbens | Michx. | Fabaceae | 8 |
| Lespedeza repens | (L.) W.P.C.Barton | Fabaceae | 8 |
| Lespedeza stuevei | Nutt. | Fabaceae | 8 |
| Lespedeza texana | Britton | Fabaceae | 8 |
| Lespedeza violacea | (L.) Pers. | Fabaceae | 8 |
| Lespedeza virginica | (L.) Britton | Fabaceae | 8 |
| Leucaena pulverulenta | (Schltdl.) Benth. | Fabaceae | 8 |
| Leucaena retusa | Benth. | Fabaceae | 8 |
| Leucophyllum candidum | I.M.Johnst. | Scrophulariaceae | 8 |
| Leucophyllum frutescens | (Berland.) I.M.Johnst. | Scrophulariaceae | 8 |
| Leucophyllum minus | A.Gray | Scrophulariaceae | 8 |
| Leucospora multifida | (Michx.) Nutt. | Plantaginaceae | 8 |
| Leymus triticoides | (Buckley) Pilg. | Poaceae | 8 |
| Liatris acidota | Engelm. & Gray | Asteraceae | 8 |
| Liatris aspera | Michx. | Asteraceae | 8 |
| Liatris bridgesii | (Mayfield) G.L.Nesom | Asteraceae | 8 |
| Liatris carrizana | (Gaiser) G.L.Nesom | Asteraceae | 8 |
| Liatris cymosa | K.Schum. | Asteraceae | 8 |
| Liatris hesperelegans | G.L.Nesom | Asteraceae | 8 |
| Liatris punctata | Hook. | Asteraceae | 8 |
| Liatris pycnostachya | Michx. | Asteraceae | 8 |
| Liatris spicata | (L.) Willd. | Asteraceae | 8 |
| Liatris squarrosa | (L.) Willd. | Asteraceae | 8 |
| Liatris squarrulosa | Michx. | Asteraceae | 8 |
| Lilaeopsis carolinensis | J.M.Coult. & Rose | Apiaceae | 8 |
| Lilaeopsis chinensis | (L.) Kuntze | Apiaceae | 8 |
| Lilium michauxii | Poir. | Liliaceae | 8 |
| Lilium philadelphicum | L. | Liliaceae | 8 |
| Limnodea arkansana | (Nutt.) L.H.Dewey | Poaceae | 8 |
| Limnosciadium pinnatum | (DC.) Mathias & Constance | Apiaceae | 8 |
| Limonium carolinianum | (Walter) Britton | Plumbaginaceae | 8 |
| Limonium limbatum | Small | Plumbaginaceae | 8 |
| Lindera benzoin | (L.) Blume | Lauraceae | 8 |
| Lindernia dubia | (L.) Pennell | Linderniaceae | 8 |
| Lindheimera texana | A.Gray & Engelm. | Asteraceae | 8 |
| Linum alatum | (Small) H.J.P.Winkl. | Linaceae | 8 |
| Linum allredii | Sivinski & M.O.Howard | Linaceae | 8 |
| Linum aristatum | Engelm. | Linaceae | 8 |
| Linum australe | A.Heller | Linaceae | 8 |
| Linum berlandieri | Hook. | Linaceae | 8 |
| Linum compactum | A.Nelson | Linaceae | 8 |
| Linum elongatum | H.J.P.Winkl. | Linaceae | 8 |
| Linum floridanum | (Planch.) Trel. | Linaceae | 8 |
| Linum hudsonioides | Planch. | Linaceae | 8 |
| Linum lewisii | Pursh | Linaceae | 8 |
| Linum medium | (Planch.) Britton | Linaceae | 8 |
| Linum pratense | (Norton) Small | Linaceae | 8 |
| Linum puberulum | (Engelm.) A.Heller | Linaceae | 8 |
| Linum rigidum | Pursh | Linaceae | 8 |
| Linum rupestre | Engelm. ex A.Gray | Linaceae | 8 |
| Linum striatum | Walter | Linaceae | 8 |
| Linum sulcatum | Riddell | Linaceae | 8 |
| Linum vernale | Wooton | Linaceae | 8 |
| Lippia alba | (Mill.) N.E.Br. ex Britton & P.Wilson | Verbenaceae | 8 |
| Liquidambar styraciflua | L. | Altingiaceae | 8 |
| Lithospermum canescens | Lehm. | Boraginaceae | 8 |
| Lithospermum caroliniense | (J.F.Gmel.) MacMill. | Boraginaceae | 8 |
| Lithospermum cobrense | Greene | Boraginaceae | 8 |
| Lithospermum helleri | (Small) J.I.Cohen | Boraginaceae | 8 |
| Lithospermum incisum | Lehm. | Boraginaceae | 8 |
| Lithospermum matamorense | DC. | Boraginaceae | 8 |
| Lithospermum mirabile | Small | Boraginaceae | 8 |
| Lithospermum multiflorum | Torr. ex A.Gray | Boraginaceae | 8 |
| Lithospermum occidentale | (Mack.) Weakley, Witsell & D.Estes | Boraginaceae | 8 |
| Lithospermum tuberosum | Rugel ex A.DC. | Boraginaceae | 8 |
| Lithospermum viride | Greene | Boraginaceae | 8 |
| Lobelia appendiculata | A.DC. | Campanulaceae | 8 |
| Lobelia berlandieri | A.DC. | Campanulaceae | 8 |
| Lobelia cardinalis | L. | Campanulaceae | 8 |
| Lobelia fenestralis | Cav. | Campanulaceae | 8 |
| Lobelia floridana | Chapm. | Campanulaceae | 8 |
| Lobelia puberula | Michx. | Campanulaceae | 8 |
| Lobelia reverchonii | B.L.Turner | Campanulaceae | 8 |
| Lobelia siphilitica | L. | Campanulaceae | 8 |
| Lobelia spicata | Lam. | Campanulaceae | 8 |
| Loeflingia squarrosa | Nutt. | Caryophyllaceae | 8 |
| Loeselia greggii | S.Watson | Polemoniaceae | 8 |
| Loeseliastrum schottii | (Torr.) Timbrook | Polemoniaceae | 8 |
| Lomatium foeniculaceum | (Nutt.) J.M.Coult. & Rose | Apiaceae | 8 |
| Lomatium orientale | J.M.Coult. & Rose | Apiaceae | 8 |
| Lonicera albiflora | Torr. & A.Gray | Caprifoliaceae | 8 |
| Lonicera arizonica | Rehder | Caprifoliaceae | 8 |
| Lonicera flava | Sims | Caprifoliaceae | 8 |
| Lonicera sempervirens | L. | Caprifoliaceae | 8 |
| Lophophora williamsii | (Lem. ex Salm-Dyck) J.M.Coult. | Cactaceae | 8 |
| Lorandersonia baileyi | (Wooton & Standl.) Urbatsch, R.P.Roberts & Neubig | Asteraceae | 8 |
| Lorandersonia pulchella | (A.Gray) Urbatsch, R.P.Roberts & Neubig | Asteraceae | 8 |
| Lorinseria areolata | (L.) C.Presl | Blechnaceae | 8 |
| Ludwigia alternifolia | L. | Onagraceae | 8 |
| Ludwigia bonariensis | (Micheli) H.Hara | Onagraceae | 8 |
| Ludwigia decurrens | Walter | Onagraceae | 8 |
| Ludwigia glandulosa | Walter | Onagraceae | 8 |
| Ludwigia grandiflora | (Michx.) Greuter & Burdet | Onagraceae | 8 |
| Ludwigia hirtella | Raf. | Onagraceae | 8 |
| Ludwigia leptocarpa | (Nutt.) H.Hara | Onagraceae | 8 |
| Ludwigia linearis | Walter | Onagraceae | 8 |
| Ludwigia microcarpa | Michx. | Onagraceae | 8 |
| Ludwigia octovalvis | (Jacq.) P.H.Raven | Onagraceae | 8 |
| Ludwigia palustris | (L.) Elliott | Onagraceae | 8 |
| Ludwigia peploides | (Kunth) P.H.Raven | Onagraceae | 8 |
| Ludwigia pilosa | Walter | Onagraceae | 8 |
| Ludwigia repens | J.R.Forst. | Onagraceae | 8 |
| Lupinus argenteus | Pursh | Fabaceae | 8 |
| Lupinus concinnus | J.Agardh | Fabaceae | 8 |
| Lupinus havardii | S.Watson | Fabaceae | 8 |
| Lupinus subcarnosus | Hook. | Fabaceae | 8 |
| Lupinus texensis | Hook. | Fabaceae | 8 |
| Luziola fluitans | (Michx.) Terrell & H.Rob. | Poaceae | 8 |
| Luzula bulbosa | (Alph.Wood) Smyth & L.C.R.Smyth | Juncaceae | 8 |
| Luzula echinata | (Small) F.J.Herm. | Juncaceae | 8 |
| Lycium berlandieri | Dunal | Solanaceae | 8 |
| Lycium carolinianum | Walter | Solanaceae | 8 |
| Lycium pallidum | Miers | Solanaceae | 8 |
| Lycium torreyi | A.Gray | Solanaceae | 8 |
| Lycopodiella alopecuroides | (L.) Cranfill | Lycopodiaceae | 8 |
| Lycopodiella appressa | (Chapm.) Cranfill | Lycopodiaceae | 8 |
| Lycopodiella prostrata | (R.M.Harper) Cranfill | Lycopodiaceae | 8 |
| Lycopus americanus | Muhl. ex W.P.C.Barton | Lamiaceae | 8 |
| Lycopus asper | Greene | Lamiaceae | 8 |
| Lycopus rubellus | Moench | Lamiaceae | 8 |
| Lycopus virginicus | L. | Lamiaceae | 8 |
| Lygodesmia juncea | (Pursh) Sweet | Asteraceae | 8 |
| Lygodesmia texana | (Torr. & A.Gray) Greene ex Small | Asteraceae | 8 |
| Lyonia ligustrina | (L.) DC. | Ericaceae | 8 |
| Lyonia mariana | (L.) D.Don | Ericaceae | 8 |
| Lysimachia lanceolata | Walter | Primulaceae | 8 |
| Lysimachia minima | (L.) U.Manns & Anderb. | Primulaceae | 8 |
| Lysimachia radicans | Hook. | Primulaceae | 8 |
| Lysimachia tonsa | (Alph.Wood) Alph.Wood ex R.Knuth | Primulaceae | 8 |
| Lythrum alatum | Pursh | Lythraceae | 8 |
| Lythrum californicum | Torr. & A.Gray | Lythraceae | 8 |
| Lythrum lineare | L. | Lythraceae | 8 |
| Lythrum ovalifolium | (A.Gray) Shuttlew. ex Koehne | Lythraceae | 8 |
| Machaeranthera tanacetifolia | (Kunth) Nees | Asteraceae | 8 |
| Maclura pomifera | (Raf.) C.K.Schneid. | Moraceae | 8 |
| Macroptilium gibbosifolium | (Ortega) A.Delgado | Fabaceae | 8 |
| Magnolia fraseri | Walter | Magnoliaceae | 8 |
| Magnolia grandiflora | L. | Magnoliaceae | 8 |
| Magnolia virginiana | L. | Magnoliaceae | 8 |
| Maianthemum racemosum | (L.) Link | Asparagaceae | 8 |
| Malachra capitata | (L.) L. | Malvaceae | 8 |
| Malacomeles pringlei | (Koehne) B.L.Turner | Rosaceae | 8 |
| Malacothrix fendleri | A.Gray | Asteraceae | 8 |
| Malaxis macrostachya | (Lex.) Kuntze | Orchidaceae | 8 |
| Malaxis unifolia | Michx. | Orchidaceae | 8 |
| Malpighia glabra | L. | Malpighiaceae | 8 |
| Malus ioensis | (Alph.Wood) Britton | Rosaceae | 8 |
| Malvastrum americanum | (L.) Torr. | Malvaceae | 8 |
| Malvastrum aurantiacum | Walp. | Malvaceae | 8 |
| Malvastrum coromandelianum | (L.) Garcke | Malvaceae | 8 |
| Malvaviscus arboreus | Dill. ex Cav. | Malvaceae | 8 |
| Malvaviscus penduliflorus | DC. | Malvaceae | 8 |
| Malvella lepidota | (A.Gray) Fryxell | Malvaceae | 8 |
| Malvella leprosa | (Ortega) Krapov. | Malvaceae | 8 |
| Malvella sagittifolia | (A.Gray) Fryxell | Malvaceae | 8 |
| Mammillaria heyderi | Muehlenpf. | Cactaceae | 8 |
| Mammillaria lasiacantha | Engelm. | Cactaceae | 8 |
| Mammillaria pottsii | Scheer ex Salm-Dyck | Cactaceae | 8 |
| Mammillaria sphaerica | A.Dietr. | Cactaceae | 8 |
| Mandevilla hypoleuca | (Benth.) Pichon | Apocynaceae | 8 |
| Mandevilla lanuginosa | (M.Martens & Galeotti) Pichon | Apocynaceae | 8 |
| Mandevilla macrosiphon | (Torr.) Pichon | Apocynaceae | 8 |
| Manihot walkerae | Croizat | Euphorbiaceae | 8 |
| Marshallia caespitosa | Nutt. ex DC. | Asteraceae | 8 |
| Marshallia graminifolia | (Walter) Small | Asteraceae | 8 |
| Marsilea macropoda | Engelm. ex A.Braun | Marsileaceae | 8 |
| Marsilea vestita | Hook. & Grev. | Marsileaceae | 8 |
| Matelea edwardsensis | Correll | Apocynaceae | 8 |
| Matricaria discoidea | DC. | Asteraceae | 8 |
| Maurandella antirrhiniflora | (Humb. & Bonpl. ex Willd.) Rothm. | Plantaginaceae | 8 |
| Mayaca fluviatilis | Aubl. | Mayacaceae | 8 |
| Maytenus phyllanthoides | Benth. | Celastraceae | 8 |
| Mecardonia acuminata | (Walter) Small | Plantaginaceae | 8 |
| Mecardonia procumbens | (Mill.) Small | Plantaginaceae | 8 |
| Medranoa palmeri | (A.Gray) G.L.Nesom | Asteraceae | 8 |
| Melampodium cinereum | DC. | Asteraceae | 8 |
| Melampodium leucanthum | Torr. & A.Gray | Asteraceae | 8 |
| Melampodium strigosum | Stuessy | Asteraceae | 8 |
| Melanthium virginicum | L. | Melanthiaceae | 8 |
| Melica bulbosa | Porter & J.M.Coult. | Poaceae | 8 |
| Melica mutica | Walter | Poaceae | 8 |
| Melica nitens | (Scribn.) Nutt. ex Piper | Poaceae | 8 |
| Melochia pyramidata | L. | Malvaceae | 8 |
| Melochia tomentosa | L. | Malvaceae | 8 |
| Melothria pendula | L. | Cucurbitaceae | 8 |
| Menispermum canadense | L. | Menispermaceae | 8 |
| Menodora heterophylla | Moric. ex DC. | Oleaceae | 8 |
| Menodora longiflora | Engelm. ex A.Gray | Oleaceae | 8 |
| Menodora scabra | Engelm. ex A.Gray | Oleaceae | 8 |
| Mentha canadensis | L. | Lamiaceae | 8 |
| Mentzelia albescens | (Gillies ex Arn.) Benth. & Hook.f. ex Griseb. | Loasaceae | 8 |
| Mentzelia albicaulis | (Douglas ex Hook.) Douglas ex Torr. & A.Gray | Loasaceae | 8 |
| Mentzelia decapetala | (Sims) Urb. | Loasaceae | 8 |
| Mentzelia humilis | (Urb. & Gilg) J.Darl. | Loasaceae | 8 |
| Mentzelia longiloba | J.Darl. | Loasaceae | 8 |
| Mentzelia montana | (Davidson) Davidson | Loasaceae | 8 |
| Mentzelia nuda | (Pursh) Torr. & A.Gray | Loasaceae | 8 |
| Mentzelia oligosperma | Nutt. ex Sims | Loasaceae | 8 |
| Mentzelia procera | (Wooton & Standl.) J.J.Schenk & L.Hufford | Loasaceae | 8 |
| Mentzelia strictissima | (Wooton & Standl.) J.Darl. | Loasaceae | 8 |
| Mentzelia texana | Urb. & Gilg | Loasaceae | 8 |
| Metastelma barbigerum | Scheele | Apocynaceae | 8 |
| Metastelma palmeri | S.Watson | Apocynaceae | 8 |
| Meximalva filipes | (A.Gray) Fryxell | Malvaceae | 8 |
| Micranthemum umbrosum | (J.F.Gmel.) S.F.Blake | Linderniaceae | 8 |
| Micranthes texana | (Buckley) Small | Saxifragaceae | 8 |
| Mikania cordifolia | (L.f.) Willd. | Asteraceae | 8 |
| Mikania scandens | (L.) Willd. | Asteraceae | 8 |
| Mimophytum alienoides | (G.L.Nesom) G.L.Nesom | Boraginaceae | 8 |
| Mimosa aculeaticarpa | Ortega | Fabaceae | 8 |
| Mimosa berlandieri | A.Gray | Fabaceae | 8 |
| Mimosa biuncifera | Benth. | Fabaceae | 8 |
| Mimosa borealis | A.Gray | Fabaceae | 8 |
| Mimosa dysocarpa | Benth. | Fabaceae | 8 |
| Mimosa malacophylla | A.Gray | Fabaceae | 8 |
| Mimosa nuttallii | (Raspail) B.L.Turner | Fabaceae | 8 |
| Mimosa strigillosa | Torr. & A.Gray | Fabaceae | 8 |
| Mimosa texana | (A.Gray) Small | Fabaceae | 8 |
| Mimosa zygophylla | Benth. | Fabaceae | 8 |
| Mimulus alatus | Aiton | Phrymaceae | 8 |
| Mimulus ringens | L. | Phrymaceae | 8 |
| Mirabilis albida | (Walter) Heimerl | Nyctaginaceae | 8 |
| Mirabilis gigantea | (Standl.) Shinners | Nyctaginaceae | 8 |
| Mirabilis glabra | (S.Watson) Standl. | Nyctaginaceae | 8 |
| Mirabilis linearis | (Pursh) Heimerl | Nyctaginaceae | 8 |
| Mirabilis longiflora | L. | Nyctaginaceae | 8 |
| Mirabilis melanotricha | (Standl.) Spellenb. | Nyctaginaceae | 8 |
| Mirabilis multiflora | (Torr.) A.Gray | Nyctaginaceae | 8 |
| Mirabilis oxybaphoides | (A.Gray) A.Gray | Nyctaginaceae | 8 |
| Mitchella repens | L. | Rubiaceae | 8 |
| Mitreola petiolata | (J.F.Gmel.) Torr. & A.Gray | Loganiaceae | 8 |
| Mitreola sessilifolia | (J.F.Gmel.) G.Don | Loganiaceae | 8 |
| Mollugo verticillata | L. | Molluginaceae | 8 |
| Monarda bradburyana | L.C.Beck | Lamiaceae | 8 |
| Monarda citriodora | Cerv. ex Lag. | Lamiaceae | 8 |
| Monarda clinopodioides | A.Gray | Lamiaceae | 8 |
| Monarda fistulosa | L. | Lamiaceae | 8 |
| Monarda fruticulosa | Epling | Lamiaceae | 8 |
| Monarda luteola | Singhurst & W.C.Holmes | Lamiaceae | 8 |
| Monarda maritima | (Cory) Correll | Lamiaceae | 8 |
| Monarda pectinata | Nutt. | Lamiaceae | 8 |
| Monarda punctata | L. | Lamiaceae | 8 |
| Monarda russeliana | Nutt. ex Sims | Lamiaceae | 8 |
| Monotropa uniflora | L. | Ericaceae | 8 |
| Morisonia incana | (Kunth) Christenh. & Byng | Capparaceae | 8 |
| Mortonia greggii | A.Gray | Celastraceae | 8 |
| Mortonia scabrella | A.Gray | Celastraceae | 8 |
| Morus microphylla | Buckley | Moraceae | 8 |
| Morus rubra | L. | Moraceae | 8 |
| Mostacillastrum subauriculatum | Al-Shehbaz | Brassicaceae | 8 |
| Muenchhusia laevis | (All.) M.M.Hanes & R.L.Barrett | Malvaceae | 8 |
| Muenchhusia moscheutos | (L.) M.M.Hanes & R.L.Barrett | Malvaceae | 8 |
| Muhlenbergia alopecuroides | (Griseb.) P.M.Peterson & Columbus | Poaceae | 8 |
| Muhlenbergia arenacea | (Buckley) Hitchc. | Poaceae | 8 |
| Muhlenbergia arenicola | Buckley | Poaceae | 8 |
| Muhlenbergia asperifolia | (Nees & Meyen ex Trin.) Parodi | Poaceae | 8 |
| Muhlenbergia bushii | R.W.Pohl | Poaceae | 8 |
| Muhlenbergia capillaris | (Lam.) Trin. | Poaceae | 8 |
| Muhlenbergia depauperata | Scribn. | Poaceae | 8 |
| Muhlenbergia emersleyi | Vasey | Poaceae | 8 |
| Muhlenbergia expansa | (Poir.) Trin. | Poaceae | 8 |
| Muhlenbergia frondosa | (Poir.) Fernald | Poaceae | 8 |
| Muhlenbergia lindheimeri | Hitchc. | Poaceae | 8 |
| Muhlenbergia longiligula | Hitchc. | Poaceae | 8 |
| Muhlenbergia mexicana | (L.) Trin. | Poaceae | 8 |
| Muhlenbergia minutissima | (Steud.) Swallen | Poaceae | 8 |
| Muhlenbergia montana | (Nutt.) Hitchc. | Poaceae | 8 |
| Muhlenbergia multiflora | Columbus | Poaceae | 8 |
| Muhlenbergia paniculata | (Nutt.) P.M.Peterson | Poaceae | 8 |
| Muhlenbergia porteri | Scribn. | Poaceae | 8 |
| Muhlenbergia racemosa | (Michx.) Britton, Sterns & Poggenb. | Poaceae | 8 |
| Muhlenbergia reverchonii | Vasey & Scribn. | Poaceae | 8 |
| Muhlenbergia rigens | (Benth.) Hitchc. | Poaceae | 8 |
| Muhlenbergia rigida | (Kunth) Kunth | Poaceae | 8 |
| Muhlenbergia schreberi | J.F.Gmel. | Poaceae | 8 |
| Muhlenbergia sericea | (Michx.) P.M.Peterson | Poaceae | 8 |
| Muhlenbergia setifolia | Vasey | Poaceae | 8 |
| Muhlenbergia spiciformis | Trin. | Poaceae | 8 |
| Muhlenbergia sylvatica | Torr. | Poaceae | 8 |
| Muhlenbergia torreyi | (Kunth) Hitchc. ex Bush | Poaceae | 8 |
| Muhlenbergia tricholepis | (Torr.) P.M.Peterson | Poaceae | 8 |
| Muhlenbergia utilis | (Torr.) Hitchc. | Poaceae | 8 |
| Muhlenbergia wrightii | Vasey ex J.M.Coult. | Poaceae | 8 |
| Munroa pulchella | (Kunth) Amarilla | Poaceae | 8 |
| Munroa squarrosa | (Nutt.) Torr. | Poaceae | 8 |
| Myosotis macrosperma | Engelm. | Boraginaceae | 8 |
| Myosotis verna | Nutt. | Boraginaceae | 8 |
| Myrica caroliniensis | Mill. | Myricaceae | 8 |
| Myrica cerifera | L. | Myricaceae | 8 |
| Myriophyllum heterophyllum | Michx. | Haloragaceae | 8 |
| Myriophyllum sibiricum | Kom. | Haloragaceae | 8 |
| Myriophyllum verticillatum | L. | Haloragaceae | 8 |
| Myriopteris alabamensis | (Buckley) Grusz & Windham | Pteridaceae | 8 |
| Myriopteris aurea | (Poir.) Grusz & Windham | Pteridaceae | 8 |
| Myriopteris fendleri | Fourn. | Pteridaceae | 8 |
| Myriopteris lanosa | (Michx.) Grusz & Windham | Pteridaceae | 8 |
| Myriopteris lendigera | (Cav.) J.Sm. | Pteridaceae | 8 |
| Myriopteris lindheimeri | J.Sm. | Pteridaceae | 8 |
| Myriopteris rufa | Fée | Pteridaceae | 8 |
| Myriopteris tomentosa | (Link) Fée | Pteridaceae | 8 |
| Myriopteris windhamii | Grusz | Pteridaceae | 8 |
| Myriopteris wootonii | (Maxon) Grusz & Windham | Pteridaceae | 8 |
| Myriopteris wrightii | (Hook.) Grusz & Windham | Pteridaceae | 8 |
| Myriopteris yavapensis | (T.Reeves ex Windham) Grusz & Windham | Pteridaceae | 8 |
| Myriopus volubilis | (L.) Small | Heliotropiaceae | 8 |
| Nabalus altissimus | (L.) Hook. | Asteraceae | 8 |
| Nabalus barbatus | (Torr. & A.Gray) A.Heller | Asteraceae | 8 |
| Nabalus carrii | (Singhurst, O'Kennon & W.C.Holmes) Weakley | Asteraceae | 8 |
| Najas guadalupensis | (Spreng.) Magnus | Hydrocharitaceae | 8 |
| Najas marina | L. | Hydrocharitaceae | 8 |
| Nama carnosa | (Wooton) C.L.Hitchc. | Namaceae | 8 |
| Nama dichotoma | (Ruiz & Pav.) Choisy | Namaceae | 8 |
| Nama havardii | A.Gray | Namaceae | 8 |
| Nama hispida | A.Gray | Namaceae | 8 |
| Nama jamaicensis | L. | Namaceae | 8 |
| Nama stenocarpa | A.Gray | Namaceae | 8 |
| Nama stevensii | C.L.Hitchc. | Namaceae | 8 |
| Nama xylopoda | (Wooton & Standl.) C.L.Hitchc. | Namaceae | 8 |
| Nanogalactia heterophylla | (Gillies ex Hook.) L.P.Queiroz | Fabaceae | 8 |
| Nassella leucotricha | (Trin. & Rupr.) R.W.Pohl | Poaceae | 8 |
| Nassella tenuissima | (Trin.) Barkworth | Poaceae | 8 |
| Nekemias arborea | (L.) J.Wen & Boggan | Vitaceae | 8 |
| Neltuma glandulosa | (Torr.) Britton & Rose | Fabaceae | 8 |
| Neltuma odorata | (Torr. & Frém.) C.E.Hughes & G.P.Lewis | Fabaceae | 8 |
| Nelumbo lutea | (Willd.) Pers. | Nelumbonaceae | 8 |
| Nemastylis geminiflora | Nutt. | Iridaceae | 8 |
| Nemastylis tenuis | (Herb.) Benth. & Hook.f. ex S.Watson | Iridaceae | 8 |
| Nemophila aphylla | (L.) Brummitt | Hydrophyllaceae | 8 |
| Nemophila phacelioides | Nutt. | Hydrophyllaceae | 8 |
| Nemophila sayersensis | B.B.Simpson, Neff & Helfgott | Hydrophyllaceae | 8 |
| Neokochia americana | (S.Watson) G.L.Chu & S.C.Sand. | Chenopodiaceae | 8 |
| Neottia bifolia | (Raf.) Baumbach | Orchidaceae | 8 |
| Nephroia carolina | (L.) L.Lian & Wei Wang | Menispermaceae | 8 |
| Nephroia diversifolia | (DC.) L.Lian & Wei Wang | Menispermaceae | 8 |
| Nephrolepis exaltata | (L.) Schott | Nephrolepidaceae | 8 |
| Neptunia lutea | (Leavenw.) Benth. | Fabaceae | 8 |
| Neptunia pubescens | Benth. | Fabaceae | 8 |
| Nerisyrenia camporum | (A.Gray) Greene | Brassicaceae | 8 |
| Nerisyrenia linearifolia | Greene | Brassicaceae | 8 |
| Nicotiana attenuata | Torr. ex S.Watson | Solanaceae | 8 |
| Nicotiana obtusifolia | M.Martens & Galeotti | Solanaceae | 8 |
| Nicotiana plumbaginifolia | Viv. | Solanaceae | 8 |
| Nissolia platycalyx | S.Watson | Fabaceae | 8 |
| Noccaea fendleri | (A.Gray) Holub | Brassicaceae | 8 |
| Nolina erumpens | (Torr.) S.Watson | Asparagaceae | 8 |
| Nolina lindheimeriana | (Scheele) S.Watson | Asparagaceae | 8 |
| Nolina micrantha | I.M.Johnst. | Asparagaceae | 8 |
| Nolina texana | S.Watson | Asparagaceae | 8 |
| Nothocalais cuspidata | (Pursh) Greene | Asteraceae | 8 |
| Notholaena aschenborniana | Klotzsch | Pteridaceae | 8 |
| Notholaena candida | (M.Martens & Galeotti) Hook. | Pteridaceae | 8 |
| Nothoscordum bivalve | (L.) Britton | Amaryllidaceae | 8 |
| Nuphar advena | (Aiton) W.T.Aiton | Nymphaeaceae | 8 |
| Nuttallanthus canadensis | (L.) D.A.Sutton | Plantaginaceae | 8 |
| Nuttallanthus texanus | (Scheele) D.A.Sutton | Plantaginaceae | 8 |
| Nyctaginia capitata | Choisy | Nyctaginaceae | 8 |
| Nymphaea ampla | (Salisb.) DC. | Nymphaeaceae | 8 |
| Nymphaea elegans | Hook. | Nymphaeaceae | 8 |
| Nymphaea mexicana | Zucc. | Nymphaeaceae | 8 |
| Nymphaea odorata | Aiton | Nymphaeaceae | 8 |
| Nymphoides aquatica | (J.F.Gmel.) Kuntze | Menyanthaceae | 8 |
| Nymphoides humboldtiana | (Kunth) Kuntze | Menyanthaceae | 8 |
| Nyssa aquatica | L. | Nyssaceae | 8 |
| Nyssa biflora | Walter | Nyssaceae | 8 |
| Nyssa sylvatica | Marshall | Nyssaceae | 8 |
| Obolaria virginica | L. | Gentianaceae | 8 |
| Odontostephana decipiens | Alexander | Apocynaceae | 8 |
| Odontostephana hirtelliflora | (McDonnell & Fishbein) Morillo | Apocynaceae | 8 |
| Odontostephana reticulata | (Engelm. ex A.Gray) Morillo, Liede & Meve | Apocynaceae | 8 |
| Oenothera albicaulis | Nutt. ex Pursh | Onagraceae | 8 |
| Oenothera biennis | L. | Onagraceae | 8 |
| Oenothera boquillensis | (P.H.Raven & D.P.Greg.) W.L.Wagner & Hoch | Onagraceae | 8 |
| Oenothera brachycarpa | A.Gray | Onagraceae | 8 |
| Oenothera calcicola | (P.H.Raven & D.P.Greg.) W.L.Wagner & Hoch | Onagraceae | 8 |
| Oenothera canescens | Torr. | Onagraceae | 8 |
| Oenothera capillifolia | Scheele | Onagraceae | 8 |
| Oenothera cespitosa | Nutt. | Onagraceae | 8 |
| Oenothera cinerea | (Wooton & Standl.) W.L.Wagner & Hoch | Onagraceae | 8 |
| Oenothera coryi | W.L.Wagner | Onagraceae | 8 |
| Oenothera curtiflora | W.L.Wagner & Hoch | Onagraceae | 8 |
| Oenothera drummondii | Hook. | Onagraceae | 8 |
| Oenothera elata | Kunth | Onagraceae | 8 |
| Oenothera engelmannii | (Small) Munz | Onagraceae | 8 |
| Oenothera filiformis | (Small) W.L.Wagner & Hoch | Onagraceae | 8 |
| Oenothera gayleana | B.L.Turner & M.J.Moore | Onagraceae | 8 |
| Oenothera glaucifolia | W.L.Wagner & Hoch | Onagraceae | 8 |
| Oenothera grandis | Smyth | Onagraceae | 8 |
| Oenothera hartwegii | Benth. | Onagraceae | 8 |
| Oenothera jamesii | Torr. & A.Gray | Onagraceae | 8 |
| Oenothera kunthiana | (Spach) Munz | Onagraceae | 8 |
| Oenothera laciniata | Hill | Onagraceae | 8 |
| Oenothera lavandulifolia | Torr. & A.Gray | Onagraceae | 8 |
| Oenothera lindheimeri | (Engelm. & A.Gray) W.L.Wagner & Hoch | Onagraceae | 8 |
| Oenothera linifolia | Nutt. | Onagraceae | 8 |
| Oenothera macrocarpa | Nutt. | Onagraceae | 8 |
| Oenothera mckelveyae | (Munz) W.L.Wagner & Hoch | Onagraceae | 8 |
| Oenothera pallida | Lindl. | Onagraceae | 8 |
| Oenothera podocarpa | (Wooton & Standl.) Krakos & W.L.Wagner | Onagraceae | 8 |
| Oenothera primiveris | A.Gray | Onagraceae | 8 |
| Oenothera pubescens | Wild. ex Spreng. | Onagraceae | 8 |
| Oenothera rhombipetala | Nutt. ex Torr. & A.Gray | Onagraceae | 8 |
| Oenothera rosea | Aiton | Onagraceae | 8 |
| Oenothera serrulata | Nutt. | Onagraceae | 8 |
| Oenothera speciosa | Nutt. | Onagraceae | 8 |
| Oenothera suffrutescens | (Ser.) W.L.Wagner & Hoch | Onagraceae | 8 |
| Oenothera suffulta | (Engelm.) W.L.Wagner & Hoch | Onagraceae | 8 |
| Oenothera tetraptera | Cav. | Onagraceae | 8 |
| Oenothera triloba | Nutt. | Onagraceae | 8 |
| Oenothera tubicula | A.Gray | Onagraceae | 8 |
| Oenothera villosa | Thunb. | Onagraceae | 8 |
| Oldenlandia boscii | (DC.) Chapm. | Rubiaceae | 8 |
| Oligomeris linifolia | (Vahl ex Hornem.) J.F.Macbr. | Resedaceae | 8 |
| Onoclea sensibilis | L. | Onocleaceae | 8 |
| Operculina pinnatifida | (Kunth) O'Donell | Convolvulaceae | 8 |
| Ophioglossum crotalophoroides | Walter | Ophioglossaceae | 8 |
| Ophioglossum engelmannii | Prantl | Ophioglossaceae | 8 |
| Ophioglossum polyphyllum | A.Braun ex Seub. | Ophioglossaceae | 8 |
| Ophioglossum vulgatum | L. | Ophioglossaceae | 8 |
| Oplismenus compositus | (L.) P.Beauv. | Poaceae | 8 |
| Opuntia arenaria | Engelm. | Cactaceae | 8 |
| Opuntia cespitosa | Raf. | Cactaceae | 8 |
| Opuntia chisosensis | (M.S.Anthony) D.J.Ferguson | Cactaceae | 8 |
| Opuntia cymochila | Engelm. & J.M.Bigelow | Cactaceae | 8 |
| Opuntia drummondii | Graham | Cactaceae | 8 |
| Opuntia engelmannii | Salm-Dyck ex Engelm. | Cactaceae | 8 |
| Opuntia fragilis | (Nutt.) Haw. | Cactaceae | 8 |
| Opuntia macrocentra | Engelm. | Cactaceae | 8 |
| Opuntia macrorhiza | Engelm. | Cactaceae | 8 |
| Opuntia orbiculata | Salm-Dyck ex Pfeiff. | Cactaceae | 8 |
| Opuntia phaeacantha | Engelm. | Cactaceae | 8 |
| Opuntia polyacantha | Haw. | Cactaceae | 8 |
| Opuntia pottsii | Salm-Dyck | Cactaceae | 8 |
| Opuntia rufida | Engelm. | Cactaceae | 8 |
| Opuntia stricta | (Haw.) Haw. | Cactaceae | 8 |
| Opuntia strigil | Engelm. | Cactaceae | 8 |
| Opuntia tortispina | Engelm. & J.M.Bigelow | Cactaceae | 8 |
| Orbexilum pedunculatum | (Mill.) Rydb. | Fabaceae | 8 |
| Orbexilum simplex | (Nutt.) Rydb. | Fabaceae | 8 |
| Oreocarya crassipes | (I.M.Johnst.) Hasenstab & M.G.Simpson | Boraginaceae | 8 |
| Oreocarya oblata | (M.E.Jones) J.F.Macbr. | Boraginaceae | 8 |
| Oreocarya palmeri | (A.Gray) Greene | Boraginaceae | 8 |
| Oreocarya suffruticosa | (Torr.) Greene | Boraginaceae | 8 |
| Orobanche cooperi | (A.Gray) A.Heller | Orobanchaceae | 8 |
| Orobanche fasciculata | Nutt. | Orobanchaceae | 8 |
| Orobanche ludoviciana | Nutt. | Orobanchaceae | 8 |
| Orobanche uniflora | L. | Orobanchaceae | 8 |
| Orontium aquaticum | L. | Araceae | 8 |
| Osmorhiza longistylis | DC. | Apiaceae | 8 |
| Osmunda spectabilis | Willd. | Osmundaceae | 8 |
| Osmundastrum cinnamomeum | (L.) C.Presl | Osmundaceae | 8 |
| Ostrya knowltonii | Coville | Betulaceae | 8 |
| Ostrya virginiana | (Mill.) K.Koch | Betulaceae | 8 |
| Oxalis dichondrifolia | A.Gray | Oxalidaceae | 8 |
| Oxalis dillenii | Jacq. | Oxalidaceae | 8 |
| Oxalis drummondii | A.Gray | Oxalidaceae | 8 |
| Oxalis florida | Salisb. | Oxalidaceae | 8 |
| Oxalis frutescens | L. | Oxalidaceae | 8 |
| Oxalis latifolia | Kunth | Oxalidaceae | 8 |
| Oxalis texana | (Small) R.Knuth | Oxalidaceae | 8 |
| Oxalis violacea | L. | Oxalidaceae | 8 |
| Oxybaphus nyctagineus | (Michx.) Sweet | Nyctaginaceae | 8 |
| Oxypolis rigidior | (L.) Raf. | Apiaceae | 8 |
| Oxytropis lambertii | Pursh | Fabaceae | 8 |
| Oxytropis sericea | Nutt. | Fabaceae | 8 |
| Packera fendleri | (A.Gray) W.A.Weber & Á.Löve | Asteraceae | 8 |
| Packera glabella | (Poir.) C.Jeffrey | Asteraceae | 8 |
| Packera neomexicana | (A.Gray) W.A.Weber & Á.Löve | Asteraceae | 8 |
| Packera plattensis | (Nutt.) W.A.Weber & Á.Löve | Asteraceae | 8 |
| Packera tampicana | (DC.) C.Jeffrey | Asteraceae | 8 |
| Paepalanthus anceps | (Walter) Christenh. & Byng | Eriocaulaceae | 8 |
| Palafoxia callosa | (Nutt.) Torr. & A.Gray | Asteraceae | 8 |
| Palafoxia hookeriana | Torr. & A.Gray | Asteraceae | 8 |
| Palafoxia rosea | (Bush) Cory | Asteraceae | 8 |
| Palafoxia sphacelata | (Nutt. ex Torr.) Cory | Asteraceae | 8 |
| Palafoxia texana | DC. | Asteraceae | 8 |
| Palhinhaea cernua | (L.) Vasc. & Franco | Lycopodiaceae | 8 |
| Panicum amarum | Elliott | Poaceae | 8 |
| Panicum capillare | L. | Poaceae | 8 |
| Panicum capillarioides | Vasey | Poaceae | 8 |
| Panicum dichotomiflorum | Michx. | Poaceae | 8 |
| Panicum flexile | (Gatt.) Scribn. | Poaceae | 8 |
| Panicum gymnocarpum | Elliott | Poaceae | 8 |
| Panicum hallii | Vasey | Poaceae | 8 |
| Panicum hemitomon | Schult. | Poaceae | 8 |
| Panicum hirticaule | J.Presl | Poaceae | 8 |
| Panicum virgatum | L. | Poaceae | 8 |
| Pappophorum bicolor | E.Fourn. | Poaceae | 8 |
| Pappophorum mucronulatum | Nees | Poaceae | 8 |
| Parietaria floridana | Nutt. | Urticaceae | 8 |
| Parietaria pensylvanica | Muhl. ex Willd. | Urticaceae | 8 |
| Parkinsonia texana | (A.Gray) S.Watson | Fabaceae | 8 |
| Parnassia asarifolia | Vent. | Celastraceae | 8 |
| Parnassia grandifolia | DC. | Celastraceae | 8 |
| Paronychia drummondii | Torr. & A.Gray | Caryophyllaceae | 8 |
| Paronychia fastigiata | (Raf.) Fernald | Caryophyllaceae | 8 |
| Paronychia jamesii | Torr. & A.Gray | Caryophyllaceae | 8 |
| Paronychia lindheimeri | Engelm. ex A.Gray | Caryophyllaceae | 8 |
| Paronychia monticola | Cory | Caryophyllaceae | 8 |
| Paronychia sessiliflora | Nutt. | Caryophyllaceae | 8 |
| Paronychia setacea | Torr. & A.Gray | Caryophyllaceae | 8 |
| Paronychia virginica | Spreng. | Caryophyllaceae | 8 |
| Parthenium confertum | A.Gray | Asteraceae | 8 |
| Parthenium incanum | Kunth | Asteraceae | 8 |
| Parthenium integrifolium | L. | Asteraceae | 8 |
| Parthenocissus heptaphylla | (Planch.) Britton | Vitaceae | 8 |
| Parthenocissus quinquefolia | (L.) Planch. | Vitaceae | 8 |
| Paspalum acuminatum | Raddi | Poaceae | 8 |
| Paspalum conjugatum | P.J.Bergius | Poaceae | 8 |
| Paspalum denticulatum | Trin. | Poaceae | 8 |
| Paspalum distichum | L. | Poaceae | 8 |
| Paspalum floridanum | Michx. | Poaceae | 8 |
| Paspalum laeve | Michx. | Poaceae | 8 |
| Paspalum langei | (E.Fourn.) Nash | Poaceae | 8 |
| Paspalum monostachyum | Vasey ex Chapm. | Poaceae | 8 |
| Paspalum plicatulum | Michx. | Poaceae | 8 |
| Paspalum praecox | Walter | Poaceae | 8 |
| Paspalum pubiflorum | Rupr. ex E.Fourn. | Poaceae | 8 |
| Paspalum repens | P.J.Bergius | Poaceae | 8 |
| Paspalum setaceum | Michx. | Poaceae | 8 |
| Paspalum vaginatum | Sw. | Poaceae | 8 |
| Passiflora affinis | Engelm. | Passifloraceae | 8 |
| Passiflora filipes | Benth. | Passifloraceae | 8 |
| Passiflora foetida | L. | Passifloraceae | 8 |
| Passiflora incarnata | L. | Passifloraceae | 8 |
| Passiflora lutea | L. | Passifloraceae | 8 |
| Passiflora pallida | L. | Passifloraceae | 8 |
| Passiflora tenuiloba | Engelm. | Passifloraceae | 8 |
| Pavonia lasiopetala | Scheele | Malvaceae | 8 |
| Pectis angustifolia | Torr. | Asteraceae | 8 |
| Pectis cylindrica | Rydb. | Asteraceae | 8 |
| Pectis filipes | Harv. & Gray | Asteraceae | 8 |
| Pectis papposa | Harv. & Gray | Asteraceae | 8 |
| Pectis prostrata | Cav. | Asteraceae | 8 |
| Pectocarya heterocarpa | (I.M.Johnst.) I.M.Johnst. | Boraginaceae | 8 |
| Pectocarya platycarpa | (Munz & I.M.Johnst.) Munz & I.M.Johnst. | Boraginaceae | 8 |
| Pedicularis canadensis | L. | Orobanchaceae | 8 |
| Pediomelum argophyllum | (Pursh) J.W.Grimes | Fabaceae | 8 |
| Pediomelum cuspidatum | (Pursh) Rydb. | Fabaceae | 8 |
| Pediomelum cyphocalyx | (A.Gray) Rydb. | Fabaceae | 8 |
| Pediomelum digitatum | (Nutt.) Isely | Fabaceae | 8 |
| Pediomelum hypogaeum | (Nutt.) Rydb. | Fabaceae | 8 |
| Pediomelum latestipulatum | (Shinners) Mahler | Fabaceae | 8 |
| Pediomelum linearifolium | (Torr. & A.Gray) J.W.Grimes | Fabaceae | 8 |
| Pediomelum pentaphyllum | (L.) Rydb. | Fabaceae | 8 |
| Pediomelum rhombifolium | (Torr. & A.Gray) Rydb. | Fabaceae | 8 |
| Pediomelum tenuiflorum | (Pursh) A.N.Egan | Fabaceae | 8 |
| Peganum mexicanum | A.Gray | Nitrariaceae | 8 |
| Pelazoneuron kunthii | (Desv.) A.R.Sm. & S.E.Fawc. | Thelypteridaceae | 8 |
| Pelazoneuron ovatum | (R.P.St.John) A.R.Sm. & S.E.Fawc. | Thelypteridaceae | 8 |
| Pelecyphora dasyacantha | (Engelm.) D.Aquino & Dan.Sánchez | Cactaceae | 8 |
| Pelecyphora emskoetteriana | (Quehl) D.Aquino & Dan.Sánchez | Cactaceae | 8 |
| Pelecyphora macromeris | (Engelm.) D.Aquino & Dan.Sánchez | Cactaceae | 8 |
| Pelecyphora missouriensis | (Sweet) D.Aquino & Dan.Sánchez | Cactaceae | 8 |
| Pelecyphora tuberculosa | (Engelm.) D.Aquino & Dan.Sánchez | Cactaceae | 8 |
| Pelecyphora vivipara | (Nutt.) D.Aquino & Dan.Sánchez | Cactaceae | 8 |
| Pellaea atropurpurea | (L.) Link | Pteridaceae | 8 |
| Pellaea glabella | Mett. | Pteridaceae | 8 |
| Pellaea intermedia | Mett. | Pteridaceae | 8 |
| Pellaea ternifolia | (Cav.) Link | Pteridaceae | 8 |
| Pellaea truncata | Goodd. | Pteridaceae | 8 |
| Pellaea wrightiana | Hook. | Pteridaceae | 8 |
| Peltandra virginica | (L.) Schott | Araceae | 8 |
| Peniocereus greggii | (Engelm.) Britton & Rose | Cactaceae | 8 |
| Pennellia longifolia | (Benth.) Rollins | Brassicaceae | 8 |
| Pennellia micrantha | (A.Gray) Nieuwl. | Brassicaceae | 8 |
| Penstemon albidus | Nutt. | Plantaginaceae | 8 |
| Penstemon ambiguus | Torr. | Plantaginaceae | 8 |
| Penstemon baccharifolius | Hook. | Plantaginaceae | 8 |
| Penstemon barbatus | (Cav.) Roth | Plantaginaceae | 8 |
| Penstemon bradburyi | Pursh | Plantaginaceae | 8 |
| Penstemon buckleyi | Pennell | Plantaginaceae | 8 |
| Penstemon cobaea | Nutt. | Plantaginaceae | 8 |
| Penstemon dasyphyllus | A.Gray | Plantaginaceae | 8 |
| Penstemon digitalis | Nutt. ex Sims | Plantaginaceae | 8 |
| Penstemon fendleri | Torr. & A.Gray | Plantaginaceae | 8 |
| Penstemon havardii | A.Gray | Plantaginaceae | 8 |
| Penstemon jamesii | Benth. | Plantaginaceae | 8 |
| Penstemon lanceolatus | Benth. | Plantaginaceae | 8 |
| Penstemon laxiflorus | Pennell | Plantaginaceae | 8 |
| Penstemon murrayanus | Hook. | Plantaginaceae | 8 |
| Penstemon oklahomensis | Pennell | Plantaginaceae | 8 |
| Penstemon tenuis | Small | Plantaginaceae | 8 |
| Penstemon thurberi | Torr. | Plantaginaceae | 8 |
| Penstemon triflorus | A.Heller | Plantaginaceae | 8 |
| Penstemon tubaeflorus | Nutt. | Plantaginaceae | 8 |
| Penthorum sedoides | L. | Penthoraceae | 8 |
| Pericome caudata | A.Gray | Asteraceae | 8 |
| Perityle angustifolia | (A.Gray) Shinners | Asteraceae | 8 |
| Perityle lindheimeri | (A.Gray) Shinners | Asteraceae | 8 |
| Perityle microglossa | Benth. | Asteraceae | 8 |
| Perityle quinqueflora | (Steyerm.) Shinners | Asteraceae | 8 |
| Perityle rupestris | (A.Gray) Shinners | Asteraceae | 8 |
| Persea borbonia | (L.) Spreng. | Lauraceae | 8 |
| Persicaria amphibia | (L.) Delarbre | Polygonaceae | 8 |
| Persicaria bicornis | (Raf.) Nieuwl. | Polygonaceae | 8 |
| Persicaria glabra | (Willd.) M.Gómez | Polygonaceae | 8 |
| Persicaria hydropiperoides | (Michx.) Small | Polygonaceae | 8 |
| Persicaria lapathifolia | (L.) Delarbre | Polygonaceae | 8 |
| Persicaria pensylvanica | (L.) M.Gómez | Polygonaceae | 8 |
| Persicaria punctata | Small | Polygonaceae | 8 |
| Persicaria robustior | (Small) E.P.Bicknell | Polygonaceae | 8 |
| Persicaria sagittata | (L.) H.Gross | Polygonaceae | 8 |
| Persicaria setacea | Small | Polygonaceae | 8 |
| Persicaria virginiana | (L.) Gaertn. | Polygonaceae | 8 |
| Peteria scoparia | A.Gray | Fabaceae | 8 |
| Petiveria alliacea | L. | Petiveriaceae | 8 |
| Petrophytum caespitosum | (Nutt.) Rydb. | Rosaceae | 8 |
| Phacelia coerulea | Greene | Hydrophyllaceae | 8 |
| Phacelia congesta | Hook. | Hydrophyllaceae | 8 |
| Phacelia corrugata | A.Nelson | Hydrophyllaceae | 8 |
| Phacelia glabra | Nutt. | Hydrophyllaceae | 8 |
| Phacelia hirsuta | Nutt. | Hydrophyllaceae | 8 |
| Phacelia infundibuliformis | Torr. | Hydrophyllaceae | 8 |
| Phacelia integrifolia | Torr. | Hydrophyllaceae | 8 |
| Phacelia patuliflora | (Engelm. & A.Gray) A.Gray | Hydrophyllaceae | 8 |
| Phacelia popei | Torr. & A.Gray | Hydrophyllaceae | 8 |
| Phacelia rupestris | Greene | Hydrophyllaceae | 8 |
| Phalaris caroliniana | Walter | Poaceae | 8 |
| Phanerophlebia umbonata | Underw. | Dryopteridaceae | 8 |
| Phaseolus angustissimus | A.Gray | Fabaceae | 8 |
| Phaseolus filiformis | Benth. | Fabaceae | 8 |
| Phaseolus grayanus | Wooton & Standl. | Fabaceae | 8 |
| Phaseolus polystachios | (L.) Britton, Sterns & Poggenb. | Fabaceae | 8 |
| Phaseolus texensis | A.Delgado & W.R.Carr | Fabaceae | 8 |
| Phaulothamnus spinescens | A.Gray | Achatocarpaceae | 8 |
| Phemeranthus brevicaulis | (S.Watson) Kiger | Montiaceae | 8 |
| Phemeranthus calcaricus | (S.Ware) Kiger | Montiaceae | 8 |
| Phemeranthus calycinus | (Engelm.) Kiger | Montiaceae | 8 |
| Phemeranthus parviflorus | (Nutt.) Kiger | Montiaceae | 8 |
| Phemeranthus rugospermus | (Holz.) Kiger | Montiaceae | 8 |
| Philadelphus microphyllus | A.Gray | Hydrangeaceae | 8 |
| Philadelphus pubescens | Loisel. | Hydrangeaceae | 8 |
| Philadelphus texensis | S.Y.Hu | Hydrangeaceae | 8 |
| Phlox carolina | L. | Polemoniaceae | 8 |
| Phlox cuspidata | Scheele | Polemoniaceae | 8 |
| Phlox divaricata | L. | Polemoniaceae | 8 |
| Phlox drummondii | Hook. | Polemoniaceae | 8 |
| Phlox glabriflora | Whitehouse | Polemoniaceae | 8 |
| Phlox longifolia | Nutt. | Polemoniaceae | 8 |
| Phlox nana | Nutt. | Polemoniaceae | 8 |
| Phlox nivalis | G.Lodd. ex Sweet | Polemoniaceae | 8 |
| Phlox pilosa | L. | Polemoniaceae | 8 |
| Phlox roemeriana | Scheele | Polemoniaceae | 8 |
| Phoradendron bolleanum | (Seem.) Eichler | Santalaceae | 8 |
| Phoradendron capitellatum | Torr. ex Trel. | Santalaceae | 8 |
| Phoradendron coryae | Trel. | Santalaceae | 8 |
| Phoradendron hawksworthii | Wiens | Santalaceae | 8 |
| Phoradendron juniperinum | Engelm. ex A.Gray | Santalaceae | 8 |
| Phoradendron leucarpum | (Raf.) Reveal & M.C.Johnst. | Santalaceae | 8 |
| Phoradendron macrophyllum | (Engelm.) Cockerell | Santalaceae | 8 |
| Phragmites australis | (Cav.) Steud. | Poaceae | 8 |
| Phryma leptostachya | L. | Phrymaceae | 8 |
| Phyla cuneifolia | (Torr.) Greene | Verbenaceae | 8 |
| Phyla lanceolata | (Michx.) Greene | Verbenaceae | 8 |
| Phyla nodiflora | (L.) Greene | Verbenaceae | 8 |
| Phyllanthopsis phyllanthoides | (Nutt.) Voronts. & Petra Hoffm. | Phyllanthaceae | 8 |
| Phyllanthus abnormis | Baill. | Phyllanthaceae | 8 |
| Phyllanthus caroliniensis | Walter | Phyllanthaceae | 8 |
| Phyllanthus evanescens | Brandegee | Phyllanthaceae | 8 |
| Phyllanthus niruri | L. | Phyllanthaceae | 8 |
| Phyllanthus polygonoides | Nutt. ex Spreng. | Phyllanthaceae | 8 |
| Phyllanthus warnockii | G.L.Webster | Phyllanthaceae | 8 |
| Physalis acutifolia | (Miers) Sandwith | Solanaceae | 8 |
| Physalis angulata | L. | Solanaceae | 8 |
| Physalis cinerascens | (Dunal) Hitchc. | Solanaceae | 8 |
| Physalis cordata | Mill. | Solanaceae | 8 |
| Physalis fendleri | A.Gray | Solanaceae | 8 |
| Physalis grisea | (Waterf.) M.Martínez | Solanaceae | 8 |
| Physalis hederifolia | A.Gray | Solanaceae | 8 |
| Physalis heterophylla | Nees | Solanaceae | 8 |
| Physalis longifolia | Nutt. | Solanaceae | 8 |
| Physalis mollis | Nutt. | Solanaceae | 8 |
| Physalis neomexicana | Rydb. | Solanaceae | 8 |
| Physalis pubescens | L. | Solanaceae | 8 |
| Physalis pumila | Nutt. | Solanaceae | 8 |
| Physalis solanacea | (Schltdl.) Axelius | Solanaceae | 8 |
| Physalis virginiana | Mill. | Solanaceae | 8 |
| Physaria fendleri | (A.Gray) O'Kane & Al-Shehbaz | Brassicaceae | 8 |
| Physaria gordonii | (A.Gray) O'Kane & Al-Shehbaz | Brassicaceae | 8 |
| Physaria ovalifolia | (Rydb.) O'Kane & Al-Shehbaz | Brassicaceae | 8 |
| Physaria purpurea | (A.Gray) O'Kane & Al-Shehbaz | Brassicaceae | 8 |
| Physocarpus monogynus | (Torr.) J.M.Coult. | Rosaceae | 8 |
| Physostegia angustifolia | Fernald | Lamiaceae | 8 |
| Physostegia digitalis | Small | Lamiaceae | 8 |
| Physostegia intermedia | (Nutt.) Engelm. & A.Gray | Lamiaceae | 8 |
| Physostegia virginiana | (L.) Benth. | Lamiaceae | 8 |
| Phytolacca americana | L. | Phytolaccaceae | 8 |
| Picradeniopsis absinthifolia | (Benth.) B.G.Baldwin | Asteraceae | 8 |
| Picradeniopsis multiflora | (Hook. & Arn.) B.G.Baldwin | Asteraceae | 8 |
| Picradeniopsis oppositifolia | (Nutt.) Rydb. | Asteraceae | 8 |
| Pilea microphylla | (L.) Liebm. | Urticaceae | 8 |
| Pilea pumila | A.Gray | Urticaceae | 8 |
| Pilostyles thurberi | A.Gray | Apodanthaceae | 8 |
| Pilularia americana | A.Br. | Marsileaceae | 8 |
| Pinaropappus roseus | (Less.) Less. | Asteraceae | 8 |
| Pinguicula pumila | Michx. | Lentibulariaceae | 8 |
| Pinus cembroides | Zucc. | Pinaceae | 8 |
| Pinus echinata | Mill. | Pinaceae | 8 |
| Pinus edulis | Engelm. | Pinaceae | 8 |
| Pinus flexilis | E.James | Pinaceae | 8 |
| Pinus palustris | Mill. | Pinaceae | 8 |
| Pinus remota | (Little) D.K.Bailey & Hawksw. | Pinaceae | 8 |
| Pinus taeda | L. | Pinaceae | 8 |
| Piptatheropsis micrantha | (Trin. & Rupr.) Romasch., P.M.Peterson & Soreng | Poaceae | 8 |
| Piptochaetium avenaceum | (L.) Parodi | Poaceae | 8 |
| Piptochaetium fimbriatum | (Kunth) Hitchc. | Poaceae | 8 |
| Piptochaetium pringlei | (Beal) Parodi | Poaceae | 8 |
| Pisonia aculeata | L. | Nyctaginaceae | 8 |
| Pistacia mexicana | Kunth | Anacardiaceae | 8 |
| Pistia stratiotes | L. | Araceae | 8 |
| Pityopsis graminifolia | (Michx.) Nutt. | Asteraceae | 8 |
| Planera aquatica | J.F.Gmel. | Ulmaceae | 8 |
| Planodes virginicum | (L.) Greene | Brassicaceae | 8 |
| Plantago aristata | Michx. | Plantaginaceae | 8 |
| Plantago elongata | Pursh | Plantaginaceae | 8 |
| Plantago helleri | Small | Plantaginaceae | 8 |
| Plantago heterophylla | Nutt. | Plantaginaceae | 8 |
| Plantago hookeriana | Fisch. & C.A.Mey. | Plantaginaceae | 8 |
| Plantago ovata | Forssk. | Plantaginaceae | 8 |
| Plantago patagonica | Jacq. | Plantaginaceae | 8 |
| Plantago rhodosperma | Decne. | Plantaginaceae | 8 |
| Plantago rugelii | Decne. | Plantaginaceae | 8 |
| Plantago virginica | L. | Plantaginaceae | 8 |
| Plantago wrightiana | Decne. | Plantaginaceae | 8 |
| Platanthera blephariglottis | (Willd.) Lindl. | Orchidaceae | 8 |
| Platanthera chapmanii | (Small) Luer | Orchidaceae | 8 |
| Platanthera ciliaris | (L.) Lindl. | Orchidaceae | 8 |
| Platanthera clavellata | (Michx.) Luer | Orchidaceae | 8 |
| Platanthera cristata | (Michx.) Lindl. | Orchidaceae | 8 |
| Platanthera flava | (L.) Lindl. | Orchidaceae | 8 |
| Platanthera integra | (Nutt.) A.Gray ex L.C.Beck | Orchidaceae | 8 |
| Platanthera lacera | (Michx.) G.Don | Orchidaceae | 8 |
| Platanthera nivea | (Nutt.) Luer | Orchidaceae | 8 |
| Platanus mexicana | Moric. | Platanaceae | 8 |
| Platanus occidentalis | L. | Platanaceae | 8 |
| Plectocephalus americanus | (Nutt.) D.Don | Asteraceae | 8 |
| Pleopeltis michauxiana | (Weath.) Hickey & Sprunt | Polypodiaceae | 8 |
| Pleopeltis polylepis | (A.Roem. ex Kunze) T.Moore | Polypodiaceae | 8 |
| Pluchea baccharis | (Mill.) Pruski | Asteraceae | 8 |
| Pluchea foetida | (L.) DC. | Asteraceae | 8 |
| Pluchea odorata | (L.) Cass. | Asteraceae | 8 |
| Pluchea sericea | (Nutt.) Coville | Asteraceae | 8 |
| Plumbago zeylanica | L. | Plumbaginaceae | 8 |
| Poa arachnifera | Torr. | Poaceae | 8 |
| Poa autumnalis | Muhl. ex Elliott | Poaceae | 8 |
| Poa bigelovii | Vasey ex Scribn. | Poaceae | 8 |
| Poa fendleriana | (Steud.) Vasey | Poaceae | 8 |
| Poa interior | Rydb. | Poaceae | 8 |
| Poa nemoralis | L. | Poaceae | 8 |
| Poa pratensis | L. | Poaceae | 8 |
| Poa sylvestris | A.Gray | Poaceae | 8 |
| Podophyllum peltatum | L. | Berberidaceae | 8 |
| Pogonia ophioglossoides | (L.) Ker Gawl. | Orchidaceae | 8 |
| Polemonium pauciflorum | S.Watson | Polemoniaceae | 8 |
| Poliomintha incana | (Torr.) A.Gray | Lamiaceae | 8 |
| Polygonatum biflorum | (Walter) Elliott | Asparagaceae | 8 |
| Polygonella polygama | Engelm. & Gray | Polygonaceae | 8 |
| Polygonum aviculare | L. | Polygonaceae | 8 |
| Polygonum tenue | Michx. | Polygonaceae | 8 |
| Polypogon interruptus | Kunth | Poaceae | 8 |
| Polypremum procumbens | L. | Tetrachondraceae | 8 |
| Polystichum acrostichoides | (Michx.) Schott | Dryopteridaceae | 8 |
| Polytaenia nuttallii | DC. | Apiaceae | 8 |
| Polytaenia texana | (J.M.Coult. & Rose) Mathias & Constance | Apiaceae | 8 |
| Pomaria brachycarpa | (A.Gray) B.B.Simpson | Fabaceae | 8 |
| Pomaria jamesii | (Torr. & A.Gray) Walp. | Fabaceae | 8 |
| Pomaria melanosticta | S.Schauer | Fabaceae | 8 |
| Pombalia verticillata | (Ortega) Paula-Souza | Violaceae | 8 |
| Pontederia cordata | L. | Pontederiaceae | 8 |
| Ponthieva racemosa | (Walter) C.Mohr | Orchidaceae | 8 |
| Populus angustifolia | E.James | Salicaceae | 8 |
| Populus deltoides | W.Bartram ex Marshall | Salicaceae | 8 |
| Populus fremontii | S.Watson | Salicaceae | 8 |
| Populus tremuloides | Michx. | Salicaceae | 8 |
| Porlieria angustifolia | (Engelm.) A.Gray | Zygophyllaceae | 8 |
| Porophyllum gracile | Benth. | Asteraceae | 8 |
| Porophyllum ruderale | (Jacq.) Cass. | Asteraceae | 8 |
| Porophyllum scoparium | A.Gray | Asteraceae | 8 |
| Portulaca halimoides | L. | Portulacaceae | 8 |
| Portulaca pilosa | L. | Portulacaceae | 8 |
| Portulaca suffrutescens | Engelm. | Portulacaceae | 8 |
| Portulaca umbraticola | Kunth | Portulacaceae | 8 |
| Potamogeton berchtoldii | Fieber | Potamogetonaceae | 8 |
| Potamogeton diversifolius | Raf. | Potamogetonaceae | 8 |
| Potamogeton foliosus | Raf. | Potamogetonaceae | 8 |
| Potamogeton illinoensis | Morong | Potamogetonaceae | 8 |
| Potamogeton nodosus | Poir. | Potamogetonaceae | 8 |
| Potamogeton pusillus | L. | Potamogetonaceae | 8 |
| Potentilla norvegica | L. | Rosaceae | 8 |
| Potentilla pensylvanica | L. | Rosaceae | 8 |
| Potentilla rivalis | Nutt. | Rosaceae | 8 |
| Potentilla simplex | Michx. | Rosaceae | 8 |
| Potentilla supina | L. | Rosaceae | 8 |
| Prenanthella exigua | (A.Gray) Rydb. | Asteraceae | 8 |
| Primula meadia | (L.) A.R.Mast & Reveal | Primulaceae | 8 |
| Priva lappulacea | (L.) Pers. | Verbenaceae | 8 |
| Proboscidea althaeifolia | (Benth.) Decne. | Martyniaceae | 8 |
| Proboscidea louisianica | (Mill.) Thell. | Martyniaceae | 8 |
| Proboscidea parviflora | (Wooton) Wooton & Standl. | Martyniaceae | 8 |
| Proboscidea sabulosa | Correll | Martyniaceae | 8 |
| Proserpinaca palustris | L. | Haloragaceae | 8 |
| Proserpinaca pectinata | Lam. | Haloragaceae | 8 |
| Prunella vulgaris | L. | Lamiaceae | 8 |
| Prunus angustifolia | Marshall | Rosaceae | 8 |
| Prunus caroliniana | (Mill.) Aiton | Rosaceae | 8 |
| Prunus gracilis | Engelm. & A.Gray | Rosaceae | 8 |
| Prunus havardii | (W.Wight) S.C.Mason | Rosaceae | 8 |
| Prunus mexicana | S.Watson | Rosaceae | 8 |
| Prunus minutiflora | Engelm. ex A.Gray | Rosaceae | 8 |
| Prunus rivularis | Scheele | Rosaceae | 8 |
| Prunus serotina | Ehrh. | Rosaceae | 8 |
| Prunus texana | D.Dietr. | Rosaceae | 8 |
| Prunus virginiana | L. | Rosaceae | 8 |
| Psathyrotopsis scaposa | (A.Gray) H.Rob. | Asteraceae | 8 |
| Pseudognaphalium attenuatum | (DC.) Anderb. | Asteraceae | 8 |
| Pseudognaphalium canescens | (DC.) Anderb. | Asteraceae | 8 |
| Pseudognaphalium stramineum | (Kunth) Anderb. | Asteraceae | 8 |
| Pseudolycopodiella caroliniana | (L.) Holub | Lycopodiaceae | 8 |
| Pseudoroegneria spicata | (Pursh) Á.Löve | Poaceae | 8 |
| Pseudotsuga menziesii | (Mirb.) Franco | Pinaceae | 8 |
| Psilactis asteroides | A.Gray | Asteraceae | 8 |
| Psilactis heterocarpa | (R.L.Hartm. & M.A.Lane) D.R.Morgan | Asteraceae | 8 |
| Psilostrophe gnaphalodes | DC. | Asteraceae | 8 |
| Psilostrophe tagetina | (Nutt.) Greene | Asteraceae | 8 |
| Psilostrophe villosa | Rydb. ex Britton | Asteraceae | 8 |
| Psilotum nudum | (L.) P.Beauv. | Psilotaceae | 8 |
| Psorothamnus scoparius | (A.Gray) Rydb. | Fabaceae | 8 |
| Ptelea trifoliata | L. | Rutaceae | 8 |
| Pteridium aquilinum | (L.) Kuhn | Dennstaedtiaceae | 8 |
| Pterocaulon virgatum | (L.) DC. | Asteraceae | 8 |
| Pterospora andromedea | Nutt. | Ericaceae | 8 |
| Ptilimnium capillaceum | (Michx.) Raf. | Apiaceae | 8 |
| Ptilimnium nuttallii | (DC.) Britton | Apiaceae | 8 |
| Purshia stansburyana | (Torr.) Henrickson | Rosaceae | 8 |
| Pycnanthemum albescens | Torr. & A.Gray | Lamiaceae | 8 |
| Pycnanthemum muticum | (Michx.) Pers. | Lamiaceae | 8 |
| Pycnanthemum tenuifolium | Schrad. | Lamiaceae | 8 |
| Pycnanthemum verticillatum | (Michx.) Pers. | Lamiaceae | 8 |
| Pyrrhopappus carolinianus | (Walter) DC. | Asteraceae | 8 |
| Pyrrhopappus pauciflorus | (D.Don) DC. | Asteraceae | 8 |
| Quercus alba | L. | Fagaceae | 8 |
| Quercus arizonica | Sarg. | Fagaceae | 8 |
| Quercus arkansana | Sarg. | Fagaceae | 8 |
| Quercus buckleyi | Dorr & Nixon | Fagaceae | 8 |
| Quercus chihuahuensis | Trel. | Fagaceae | 8 |
| Quercus emoryi | Torr. | Fagaceae | 8 |
| Quercus falcata | Michx. | Fagaceae | 8 |
| Quercus fusiformis | Small | Fagaceae | 8 |
| Quercus gambelii | Nutt. | Fagaceae | 8 |
| Quercus gravesii | Sudw. | Fagaceae | 8 |
| Quercus grisea | Liebm. | Fagaceae | 8 |
| Quercus havardii | Rydb. | Fagaceae | 8 |
| Quercus hemisphaerica | W.Bartram ex Willd. | Fagaceae | 8 |
| Quercus hypoleucoides | A.Camus | Fagaceae | 8 |
| Quercus imbricaria | Michx. | Fagaceae | 8 |
| Quercus incana | W.Bartram | Fagaceae | 8 |
| Quercus intricata | Trel. | Fagaceae | 8 |
| Quercus laceyi | Small | Fagaceae | 8 |
| Quercus laurifolia | Michx. | Fagaceae | 8 |
| Quercus lyrata | Walter | Fagaceae | 8 |
| Quercus macrocarpa | Michx. | Fagaceae | 8 |
| Quercus marilandica | (L.) Münchh. | Fagaceae | 8 |
| Quercus michauxii | Nutt. | Fagaceae | 8 |
| Quercus mohriana | Buckley ex Rydb. | Fagaceae | 8 |
| Quercus muehlenbergii | Engelm. | Fagaceae | 8 |
| Quercus nigra | L. | Fagaceae | 8 |
| Quercus oblongifolia | Torr. | Fagaceae | 8 |
| Quercus pagoda | Raf. | Fagaceae | 8 |
| Quercus phellos | L. | Fagaceae | 8 |
| Quercus polymorpha | Schltdl. & Cham. | Fagaceae | 8 |
| Quercus prinoides | Willd. | Fagaceae | 8 |
| Quercus pungens | Liebm. | Fagaceae | 8 |
| Quercus rugosa | Née | Fagaceae | 8 |
| Quercus shumardii | Buckley | Fagaceae | 8 |
| Quercus similis | Ashe | Fagaceae | 8 |
| Quercus sinuata | Walter | Fagaceae | 8 |
| Quercus stellata | Wangenh. | Fagaceae | 8 |
| Quercus texana | Buckley | Fagaceae | 8 |
| Quercus toumeyi | Sarg. | Fagaceae | 8 |
| Quercus turbinella | Greene | Fagaceae | 8 |
| Quercus vaseyana | Buckley | Fagaceae | 8 |
| Quercus velutina | Lam. | Fagaceae | 8 |
| Quercus virginiana | Mill. | Fagaceae | 8 |
| Quincula lobata | (Torr.) Raf. | Solanaceae | 8 |
| Rafinesquia neomexicana | A.Gray | Asteraceae | 8 |
| Randia obcordata | S.Watson | Rubiaceae | 8 |
| Ranunculus abortivus | L. | Ranunculaceae | 8 |
| Ranunculus carolinianus | DC. | Ranunculaceae | 8 |
| Ranunculus fascicularis | Muhl. ex Bigelow | Ranunculaceae | 8 |
| Ranunculus flabellaris | Raf. | Ranunculaceae | 8 |
| Ranunculus longirostris | Godr. | Ranunculaceae | 8 |
| Ranunculus macranthus | Scheele | Ranunculaceae | 8 |
| Ranunculus minimus | E.H.L.Krause | Ranunculaceae | 8 |
| Ranunculus petiolaris | Kunth | Ranunculaceae | 8 |
| Ranunculus pusillus | Poir. | Ranunculaceae | 8 |
| Ranunculus recurvatus | Poir. | Ranunculaceae | 8 |
| Ranunculus sceleratus | L. | Ranunculaceae | 8 |
| Ranunculus trichophyllus | Chaix | Ranunculaceae | 8 |
| Ratibida columnifera | (Nutt.) Wooton & Standl. | Asteraceae | 8 |
| Ratibida peduncularis | Barnhart | Asteraceae | 8 |
| Ratibida tagetes | (E.James) Barnhart | Asteraceae | 8 |
| Rayjacksonia aurea | (A.Gray) R.L.Hartm. & M.A.Lane | Asteraceae | 8 |
| Rayjacksonia phyllocephala | (DC.) R.L.Hartm. & M.A.Lane | Asteraceae | 8 |
| Rhamnus lanceolata | Pursh | Rhamnaceae | 8 |
| Rhexia alifanus | Walter | Melastomataceae | 8 |
| Rhexia lutea | Walter | Melastomataceae | 8 |
| Rhexia mariana | L. | Melastomataceae | 8 |
| Rhexia petiolata | Walter | Melastomataceae | 8 |
| Rhexia virginica | L. | Melastomataceae | 8 |
| Rhinotropis lindheimeri | (A.Gray) J.R.Abbott | Polygalaceae | 8 |
| Rhododendron canescens | (Michx.) Sweet | Ericaceae | 8 |
| Rhododendron viscosum | (L.) Torr. | Ericaceae | 8 |
| Rhododon ciliatus | (Benth.) Epling | Lamiaceae | 8 |
| Rhus aromatica | Aiton | Anacardiaceae | 8 |
| Rhus copallinum | L. | Anacardiaceae | 8 |
| Rhus glabra | L. | Anacardiaceae | 8 |
| Rhus microphylla | Engelm. | Anacardiaceae | 8 |
| Rhus virens | Lindh. ex A.Gray | Anacardiaceae | 8 |
| Rhynchosia americana | (Mill.) Metz | Fabaceae | 8 |
| Rhynchosia latifolia | Nutt. | Fabaceae | 8 |
| Rhynchosia minima | (L.) DC. | Fabaceae | 8 |
| Rhynchosia reniformis | DC. | Fabaceae | 8 |
| Rhynchosia senna | Gillies ex Hook. & Arn. | Fabaceae | 8 |
| Rhynchosida physocalyx | (A.Gray) Fryxell | Malvaceae | 8 |
| Rhynchospora caduca | Elliott | Cyperaceae | 8 |
| Rhynchospora capillacea | Torr. | Cyperaceae | 8 |
| Rhynchospora capitellata | (Michx.) Vahl | Cyperaceae | 8 |
| Rhynchospora cephalantha | A.Gray | Cyperaceae | 8 |
| Rhynchospora chalarocephala | Fernald & Gale | Cyperaceae | 8 |
| Rhynchospora chapmanii | M.A.Curtis | Cyperaceae | 8 |
| Rhynchospora colorata | (L.) H.Pfeiff. | Cyperaceae | 8 |
| Rhynchospora corniculata | (Lam.) A.Gray | Cyperaceae | 8 |
| Rhynchospora divergens | Chapm. ex M.A.Curtis | Cyperaceae | 8 |
| Rhynchospora elliottii | A.Dietr. | Cyperaceae | 8 |
| Rhynchospora fascicularis | (Michx.) Vahl | Cyperaceae | 8 |
| Rhynchospora filifolia | A.Gray | Cyperaceae | 8 |
| Rhynchospora globularis | (Chapm.) Small | Cyperaceae | 8 |
| Rhynchospora glomerata | (L.) Vahl | Cyperaceae | 8 |
| Rhynchospora gracilenta | A.Gray | Cyperaceae | 8 |
| Rhynchospora grayi | Kunth | Cyperaceae | 8 |
| Rhynchospora harveyi | W.Boott | Cyperaceae | 8 |
| Rhynchospora inexpansa | (Michx.) Vahl | Cyperaceae | 8 |
| Rhynchospora latifolia | (Baldwin ex Elliott) W.W.Thomas | Cyperaceae | 8 |
| Rhynchospora leptocarpa | (Chapm. ex Britton) Small | Cyperaceae | 8 |
| Rhynchospora macra | (C.B.Clarke ex Britton) Small | Cyperaceae | 8 |
| Rhynchospora macrostachya | Torr. ex A.Gray | Cyperaceae | 8 |
| Rhynchospora microcarpa | Baldwin ex A.Gray | Cyperaceae | 8 |
| Rhynchospora miliacea | (Lam.) A.Gray | Cyperaceae | 8 |
| Rhynchospora mixta | Britton | Cyperaceae | 8 |
| Rhynchospora nitens | (Vahl) A.Gray | Cyperaceae | 8 |
| Rhynchospora nivea | Boeckeler | Cyperaceae | 8 |
| Rhynchospora oligantha | A.Gray | Cyperaceae | 8 |
| Rhynchospora plumosa | Elliott | Cyperaceae | 8 |
| Rhynchospora rariflora | (Michx.) Elliott | Cyperaceae | 8 |
| Rhynchospora recognita | (Gale) Kral | Cyperaceae | 8 |
| Rhynchospora tracyi | Britton | Cyperaceae | 8 |
| Ribes aureum | Pursh | Grossulariaceae | 8 |
| Ribes curvatum | Small | Grossulariaceae | 8 |
| Ribes leptanthum | A.Gray | Grossulariaceae | 8 |
| Ribes mescalerium | Coville | Grossulariaceae | 8 |
| Richardia scabra | L. | Rubiaceae | 8 |
| Richardia tricocca | (Torr. & A.Gray) Standl. | Rubiaceae | 8 |
| Rivina humilis | L. | Petiveriaceae | 8 |
| Robinia neomexicana | A.Gray | Fabaceae | 8 |
| Rorippa curvipes | Greene | Brassicaceae | 8 |
| Rorippa palustris | (L.) Besser | Brassicaceae | 8 |
| Rorippa sessiliflora | (Nutt.) Hitchc. | Brassicaceae | 8 |
| Rorippa teres | (Michx.) Stuckey | Brassicaceae | 8 |
| Rosa arkansana | Porter | Rosaceae | 8 |
| Rosa carolina | L. | Rosaceae | 8 |
| Rosa foliolosa | Nutt. | Rosaceae | 8 |
| Rosa setigera | Michx. | Rosaceae | 8 |
| Rosa stellata | Wooton | Rosaceae | 8 |
| Rosa woodsii | Lindl. | Rosaceae | 8 |
| Rotala ramosior | (L.) Koehne | Lythraceae | 8 |
| Rottboellia campestris | Nutt. | Poaceae | 8 |
| Rottboellia rugosa | Nutt. | Poaceae | 8 |
| Rubus flagellaris | Willd. | Rosaceae | 8 |
| Rubus pascuus | L.H.Bailey | Rosaceae | 8 |
| Rubus trivialis | Michx. | Rosaceae | 8 |
| Rudbeckia alismifolia | Torr. & A.Gray | Asteraceae | 8 |
| Rudbeckia amplexicaulis | Vahl | Asteraceae | 8 |
| Rudbeckia fulgida | Aiton | Asteraceae | 8 |
| Rudbeckia grandiflora | (Sweet) C.C.Gmel. ex DC. | Asteraceae | 8 |
| Rudbeckia hirta | L. | Asteraceae | 8 |
| Rudbeckia laciniata | L. | Asteraceae | 8 |
| Rudbeckia maxima | Nutt. | Asteraceae | 8 |
| Rudbeckia missouriensis | Engelm. ex C.L.Boynton & Beadle | Asteraceae | 8 |
| Rudbeckia scabrifolia | L.E.Br. | Asteraceae | 8 |
| Rudbeckia subtomentosa | Pursh | Asteraceae | 8 |
| Rudbeckia texana | (Perdue) P.B.Cox & Urbatsch | Asteraceae | 8 |
| Rudbeckia triloba | L. | Asteraceae | 8 |
| Ruellia caroliniensis | (J.F.Gmel.) Steud. | Acanthaceae | 8 |
| Ruellia ciliatiflora | Hook. | Acanthaceae | 8 |
| Ruellia corzoi | Tharp & F.A.Barkley | Acanthaceae | 8 |
| Ruellia drummondiana | (Nees) A.Gray | Acanthaceae | 8 |
| Ruellia humilis | Nutt. | Acanthaceae | 8 |
| Ruellia metziae | Tharp | Acanthaceae | 8 |
| Ruellia parryi | A.Gray | Acanthaceae | 8 |
| Ruellia pedunculata | Torr. ex A.Gray | Acanthaceae | 8 |
| Ruellia strepens | L. | Acanthaceae | 8 |
| Rumex altissimus | Alph.Wood | Polygonaceae | 8 |
| Rumex hastatulus | Baldwin | Polygonaceae | 8 |
| Rumex hymenosepalus | Torr. | Polygonaceae | 8 |
| Rumex maritimus | L. | Polygonaceae | 8 |
| Rumex triangulivalvis | (Danser) Rech.f. | Polygonaceae | 8 |
| Rumex venosus | Pursh | Polygonaceae | 8 |
| Rumex verticillatus | L. | Polygonaceae | 8 |
| Ruppia cirrhosa | (Petagna) Grande | Ruppiaceae | 8 |
| Ruppia maritima | L. | Ruppiaceae | 8 |
| Sabal mexicana | Mart. | Arecaceae | 8 |
| Sabal minor | (Jacq.) Pers. | Arecaceae | 8 |
| Sabatia angularis | (L.) Pursh | Gentianaceae | 8 |
| Sabatia calycina | (Lam.) A.Heller | Gentianaceae | 8 |
| Sabatia campanulata | (L.) Torr. | Gentianaceae | 8 |
| Sabatia campestris | Nutt. | Gentianaceae | 8 |
| Sabatia gentianoides | Elliott | Gentianaceae | 8 |
| Sabdariffa aculeata | (Walter) M.M.Hanes & R.L.Barrett | Malvaceae | 8 |
| Sabulina michauxii | (Fenzl) Dillenb. & Kadereit | Caryophyllaceae | 8 |
| Sabulina patula | (Michx.) Small ex Rydb. | Caryophyllaceae | 8 |
| Sacciolepis striata | (L.) Nash | Poaceae | 8 |
| Sagina decumbens | (Elliott) Torr. & A.Gray | Caryophyllaceae | 8 |
| Sagittaria brevirostra | Mack. & Bush | Alismataceae | 8 |
| Sagittaria chapmanii | (J.G.Sm.) C.Mohr | Alismataceae | 8 |
| Sagittaria cuneata | E.Sheld. | Alismataceae | 8 |
| Sagittaria graminea | Michx. | Alismataceae | 8 |
| Sagittaria latifolia | Willd. | Alismataceae | 8 |
| Sagittaria longiloba | Engelm. ex J.G.Sm. | Alismataceae | 8 |
| Sagittaria montevidensis | Cham. & Schltdl. | Alismataceae | 8 |
| Sagittaria papillosa | Buchenau | Alismataceae | 8 |
| Sagittaria platyphylla | (Engelm.) J.G.Sm. | Alismataceae | 8 |
| Salicornia bigelovii | Torr. | Chenopodiaceae | 8 |
| Salix amygdaloides | Andersson | Salicaceae | 8 |
| Salix caroliniana | Michx. | Salicaceae | 8 |
| Salix exigua | Nutt. | Salicaceae | 8 |
| Salix gooddingii | C.R.Ball | Salicaceae | 8 |
| Salix humilis | Marshall | Salicaceae | 8 |
| Salix interior | Rowlee | Salicaceae | 8 |
| Salix lasiolepis | Benth. | Salicaceae | 8 |
| Salix lucida | Muhl. | Salicaceae | 8 |
| Salix nigra | Marshall | Salicaceae | 8 |
| Salix taxifolia | Kunth | Salicaceae | 8 |
| Salvia arizonica | A.Gray | Lamiaceae | 8 |
| Salvia azurea | Lam. ex Vahl | Lamiaceae | 8 |
| Salvia ballotiflora | Benth. | Lamiaceae | 8 |
| Salvia coccinea | Buc'hoz ex Etl. | Lamiaceae | 8 |
| Salvia engelmannii | A.Gray | Lamiaceae | 8 |
| Salvia farinacea | Benth. | Lamiaceae | 8 |
| Salvia greggii | A.Gray | Lamiaceae | 8 |
| Salvia henryi | A.Gray | Lamiaceae | 8 |
| Salvia lycioides | A.Gray | Lamiaceae | 8 |
| Salvia lyrata | L. | Lamiaceae | 8 |
| Salvia pinguifolia | (Fernald) Wooton & Standl. | Lamiaceae | 8 |
| Salvia reflexa | Hornem. | Lamiaceae | 8 |
| Salvia regla | Cav. | Lamiaceae | 8 |
| Salvia reptans | Jacq. | Lamiaceae | 8 |
| Salvia roemeriana | Scheele | Lamiaceae | 8 |
| Salvia subincisa | Benth. | Lamiaceae | 8 |
| Salvia texana | (Scheele) Torr. | Lamiaceae | 8 |
| Salvia tiliifolia | Vahl | Lamiaceae | 8 |
| Sambucus canadensis | L. | Viburnaceae | 8 |
| Sambucus cerulea | Raf. | Viburnaceae | 8 |
| Samolus ebracteatus | Kunth | Primulaceae | 8 |
| Samolus parviflorus | Raf. | Primulaceae | 8 |
| Sanguinaria canadensis | L. | Papaveraceae | 8 |
| Sanguisorba annua | (Nutt. ex Hook.) Torr. & A.Gray | Rosaceae | 8 |
| Sanicula canadensis | L. | Apiaceae | 8 |
| Sanicula odorata | (Raf.) K.M.Pryer & L.R.Phillippe | Apiaceae | 8 |
| Sanicula smallii | E.P.Bicknell | Apiaceae | 8 |
| Sanvitalia ocymoides | DC. | Asteraceae | 8 |
| Sapindus drummondii | Hook. & Arn. | Sapindaceae | 8 |
| Sarracenia alata | (Alph.Wood) Alph.Wood | Sarraceniaceae | 8 |
| Sartwellia flaveriae | A.Gray | Asteraceae | 8 |
| Sassafras albidum | (Nutt.) Nees | Lauraceae | 8 |
| Saururus cernuus | L. | Saururaceae | 8 |
| Scaevola plumieri | (L.) Vahl | Goodeniaceae | 8 |
| Sceptridium biternatum | (Savigny) Lyon | Ophioglossaceae | 8 |
| Sceptridium dissectum | (Spreng.) Lyon | Ophioglossaceae | 8 |
| Sceptridium lunarioides | (Michx.) Holub | Ophioglossaceae | 8 |
| Schaefferia cuneifolia | A.Gray | Celastraceae | 8 |
| Schizachyrium littorale | (Nash) E.P.Bicknell | Poaceae | 8 |
| Schizachyrium sanguineum | (Retz.) Alston | Poaceae | 8 |
| Schizachyrium scoparium | (Michx.) Nash | Poaceae | 8 |
| Schkuhria pinnata | (Lam.) Kuntze ex Thell. | Asteraceae | 8 |
| Schoenocaulon ghiesbreghtii | Greenm. | Melanthiaceae | 8 |
| Schoenocaulon texanum | Scheele | Melanthiaceae | 8 |
| Schoenolirion croceum | (Michx.) Alph.Wood | Asparagaceae | 8 |
| Schoenolirion wrightii | Sherman | Asparagaceae | 8 |
| Schoenoplectus acutus | (Muhl. ex Bigelow) Á.Löve & D.Löve | Cyperaceae | 8 |
| Schoenoplectus americanus | (Pers.) Volkart | Cyperaceae | 8 |
| Schoenoplectus californicus | (C.A.Mey.) Soják | Cyperaceae | 8 |
| Schoenoplectus etuberculatus | (Steud.) Soják | Cyperaceae | 8 |
| Schoenoplectus pungens | (Vahl) Palla | Cyperaceae | 8 |
| Schoenoplectus tabernaemontani | (C.C.Gmel.) Palla | Cyperaceae | 8 |
| Schoenus nigricans | L. | Cyperaceae | 8 |
| Scirpus atrovirens | Willd. | Cyperaceae | 8 |
| Scirpus cyperinus | (L.) Kunth | Cyperaceae | 8 |
| Scirpus georgianus | R.M.Harper | Cyperaceae | 8 |
| Scirpus pendulus | Muhl. | Cyperaceae | 8 |
| Scleria baldwinii | (Torr.) Steud. | Cyperaceae | 8 |
| Scleria ciliata | Michx. | Cyperaceae | 8 |
| Scleria distans | Poir. | Cyperaceae | 8 |
| Scleria georgiana | Core | Cyperaceae | 8 |
| Scleria muehlenbergii | Steud. | Cyperaceae | 8 |
| Scleria oligantha | Michx. | Cyperaceae | 8 |
| Scleria pauciflora | Muhl. ex Willd. | Cyperaceae | 8 |
| Scleria triglomerata | Michx. | Cyperaceae | 8 |
| Scleria verticillata | Muhl. ex Willd. | Cyperaceae | 8 |
| Sclerocactus brevihamatus | (Engelm.) D.R.Hunt | Cactaceae | 8 |
| Sclerocactus intertextus | (Engelm.) N.P.Taylor | Cactaceae | 8 |
| Sclerocactus mariposensis | (Hester) N.P.Taylor | Cactaceae | 8 |
| Sclerocactus papyracanthus | (Engelm.) N.P.Taylor | Cactaceae | 8 |
| Sclerocactus scheeri | (Salm-Dyck) N.P.Taylor | Cactaceae | 8 |
| Sclerocactus warnockii | (L.D.Benson) N.P.Taylor | Cactaceae | 8 |
| Sclerocarpus uniserialis | (Hook.) Benth. & Hook.f. ex Hemsl. | Asteraceae | 8 |
| Scleropogon brevifolius | Phil. | Poaceae | 8 |
| Scoparia dulcis | L. | Plantaginaceae | 8 |
| Scrophularia marilandica | L. | Scrophulariaceae | 8 |
| Scutellaria cardiophylla | Engelm. & A.Gray | Lamiaceae | 8 |
| Scutellaria drummondii | Benth. | Lamiaceae | 8 |
| Scutellaria elliptica | Muhl. | Lamiaceae | 8 |
| Scutellaria galericulata | L. | Lamiaceae | 8 |
| Scutellaria integrifolia | L. | Lamiaceae | 8 |
| Scutellaria lateriflora | L. | Lamiaceae | 8 |
| Scutellaria mexicana | (Torr.) A.J.Paton | Lamiaceae | 8 |
| Scutellaria muriculata | Epling | Lamiaceae | 8 |
| Scutellaria ovata | Hill | Lamiaceae | 8 |
| Scutellaria parvula | Michx. | Lamiaceae | 8 |
| Scutellaria potosina | Brandegee | Lamiaceae | 8 |
| Scutellaria racemosa | Pers. | Lamiaceae | 8 |
| Scutellaria wrightii | A.Gray | Lamiaceae | 8 |
| Sedum cockerellii | Britton | Crassulaceae | 8 |
| Sedum nuttallii | Torr. & E.James ex Eaton | Crassulaceae | 8 |
| Sedum pulchellum | Michx. | Crassulaceae | 8 |
| Sedum wrightii | A.Gray | Crassulaceae | 8 |
| Selaginella apoda | Spring | Selaginellaceae | 8 |
| Selaginella arenicola | Underw. | Selaginellaceae | 8 |
| Selaginella arizonica | Maxon | Selaginellaceae | 8 |
| Selaginella corallina | (Riddell) Wilbur & Whitson | Selaginellaceae | 8 |
| Selaginella lepidophylla | (Hook. & Grev.) Spring | Selaginellaceae | 8 |
| Selaginella mutica | D.C.Eaton | Selaginellaceae | 8 |
| Selaginella peruviana | Hieron. | Selaginellaceae | 8 |
| Selaginella pilifera | A.Br. | Selaginellaceae | 8 |
| Selaginella rupincola | Underw. | Selaginellaceae | 8 |
| Selaginella scopulorum | Maxon | Selaginellaceae | 8 |
| Selaginella underwoodii | Hieron. | Selaginellaceae | 8 |
| Selaginella wrightii | Hieron. | Selaginellaceae | 8 |
| Selenicereus spinulosus | (DC.) Britton & Rose | Cactaceae | 8 |
| Senecio ampullaceus | Hook. | Asteraceae | 8 |
| Senecio flaccidus | Less. | Asteraceae | 8 |
| Senecio spartioides | Torr. & A.Gray | Asteraceae | 8 |
| Senecio warnockii | Shinners | Asteraceae | 8 |
| Senecio wootonii | Greene | Asteraceae | 8 |
| Senegalia berlandieri | (Benth.) Britton & Rose | Fabaceae | 8 |
| Senegalia greggii | (A.Gray) Britton & Rose | Fabaceae | 8 |
| Senegalia roemeriana | (Scheele) Britton & Rose | Fabaceae | 8 |
| Senegalia wrightii | (Benth.) Britton & Rose | Fabaceae | 8 |
| Senna bauhinioides | (A.Gray) H.S.Irwin & Barneby | Fabaceae | 8 |
| Senna lindheimeriana | (Scheele) H.S.Irwin & Barneby | Fabaceae | 8 |
| Senna marilandica | (L.) Link | Fabaceae | 8 |
| Senna obtusifolia | (L.) H.S.Irwin & Barneby | Fabaceae | 8 |
| Senna pilosior | (B.L.Rob.) H.S.Irwin & Barneby | Fabaceae | 8 |
| Senna pumilio | (A.Gray) H.S.Irwin & Barneby | Fabaceae | 8 |
| Senna roemeriana | (Scheele) H.S.Irwin & Barneby | Fabaceae | 8 |
| Senna wislizeni | (A.Gray) H.S.Irwin & Barneby | Fabaceae | 8 |
| Serjania brachycarpa | A.Gray ex Radlk. | Sapindaceae | 8 |
| Sesbania drummondii | (Rydb.) Cory | Fabaceae | 8 |
| Sesbania herbacea | (Mill.) McVaugh | Fabaceae | 8 |
| Sesbania vesicaria | (Jacq.) Elliott | Fabaceae | 8 |
| Sesuvium maritimum | (Walter) Britton, Sterns & Poggenb. | Aizoaceae | 8 |
| Sesuvium portulacastrum | (L.) L. | Aizoaceae | 8 |
| Setaria corrugata | (Elliott) Schult. | Poaceae | 8 |
| Setaria grisebachii | E.Fourn. | Poaceae | 8 |
| Setaria leucopila | (Scribn. & Merr.) K.Schum. | Poaceae | 8 |
| Setaria magna | Griseb. | Poaceae | 8 |
| Setaria parviflora | (Poir.) Kerguélen | Poaceae | 8 |
| Setaria reverchonii | (Vasey) Pilg. | Poaceae | 8 |
| Setaria scheelei | (Steud.) Hitchc. | Poaceae | 8 |
| Seymeria cassioides | (J.F.Gmel.) S.F.Blake | Orobanchaceae | 8 |
| Shinnersia rivularis | (A.Gray) R.M.King & H.Rob. | Asteraceae | 8 |
| Sicyos angulatus | L. | Cucurbitaceae | 8 |
| Sicyos glaber | Wooton | Cucurbitaceae | 8 |
| Sicyos laciniatus | L. | Cucurbitaceae | 8 |
| Sicyos microphyllus | Kunth | Cucurbitaceae | 8 |
| Sida ciliaris | L. | Malvaceae | 8 |
| Sida cordifolia | L. | Malvaceae | 8 |
| Sida elliottii | Torr. & A.Gray | Malvaceae | 8 |
| Sida lindheimeri | Engelm. & Gray | Malvaceae | 8 |
| Sida spinosa | L. | Malvaceae | 8 |
| Sideroxylon celastrinum | (Kunth) T.D.Penn. | Sapotaceae | 8 |
| Sideroxylon lanuginosum | Michx. | Sapotaceae | 8 |
| Sideroxylon lycioides | L. | Sapotaceae | 8 |
| Sidneya tenuifolia | (A.Gray) E.E.Schill. & Panero | Asteraceae | 8 |
| Silene antirrhina | L. | Caryophyllaceae | 8 |
| Silene laciniata | Cav. | Caryophyllaceae | 8 |
| Silene stellata | W.T.Aiton | Caryophyllaceae | 8 |
| Silene subciliata | B.L.Rob. | Caryophyllaceae | 8 |
| Silphium albiflorum | A.Gray | Asteraceae | 8 |
| Silphium asteriscus | L. | Asteraceae | 8 |
| Silphium integrifolium | Michx. | Asteraceae | 8 |
| Silphium laciniatum | L. | Asteraceae | 8 |
| Silphium perfoliatum | L. | Asteraceae | 8 |
| Silphium radula | Nutt. | Asteraceae | 8 |
| Simsia calva | A.Gray | Asteraceae | 8 |
| Sisyrinchium albidum | Raf. | Iridaceae | 8 |
| Sisyrinchium angustifolium | Mill. | Iridaceae | 8 |
| Sisyrinchium biforme | E.P.Bicknell | Iridaceae | 8 |
| Sisyrinchium campestre | E.P.Bicknell | Iridaceae | 8 |
| Sisyrinchium demissum | Greene | Iridaceae | 8 |
| Sisyrinchium ensigerum | E.P.Bicknell | Iridaceae | 8 |
| Sisyrinchium langloisii | Greene | Iridaceae | 8 |
| Sisyrinchium minus | Engelm. & A.Gray | Iridaceae | 8 |
| Sisyrinchium myrioflorum | E.L.Keith | Iridaceae | 8 |
| Sisyrinchium pruinosum | E.P.Bicknell | Iridaceae | 8 |
| Sisyrinchium sagittiferum | E.P.Bicknell | Iridaceae | 8 |
| Sisyrinchium scabrum | Schltdl. & Cham. | Iridaceae | 8 |
| Sium suave | Walter | Apiaceae | 8 |
| Smallanthus uvedalia | (L.) Mack. | Asteraceae | 8 |
| Smilax bona-nox | L. | Smilacaceae | 8 |
| Smilax glauca | Walter | Smilacaceae | 8 |
| Smilax laurifolia | L. | Smilacaceae | 8 |
| Smilax maritima | Feay ex Alph.Wood | Smilacaceae | 8 |
| Smilax pumila | Walter | Smilacaceae | 8 |
| Smilax rotundifolia | L. | Smilacaceae | 8 |
| Smilax tamnoides | L. | Smilacaceae | 8 |
| Smilax walteri | Pursh | Smilacaceae | 8 |
| Solanum americanum | Mill. | Solanaceae | 8 |
| Solanum campechiense | L. | Solanaceae | 8 |
| Solanum carolinense | L. | Solanaceae | 8 |
| Solanum citrullifolium | A.Braun | Solanaceae | 8 |
| Solanum davisense | Whalen | Solanaceae | 8 |
| Solanum dimidiatum | Raf. | Solanaceae | 8 |
| Solanum douglasii | Dunal | Solanaceae | 8 |
| Solanum elaeagnifolium | Cav. | Solanaceae | 8 |
| Solanum emulans | Raf. | Solanaceae | 8 |
| Solanum erianthum | D.Don | Solanaceae | 8 |
| Solanum jamesii | Torr. | Solanaceae | 8 |
| Solanum nigrescens | M.Martens & Galeotti | Solanaceae | 8 |
| Solanum pseudogracile | Heiser | Solanaceae | 8 |
| Solanum rostratum | Dunal | Solanaceae | 8 |
| Solanum stoloniferum | Schltdl. | Solanaceae | 8 |
| Solanum triflorum | Nutt. | Solanaceae | 8 |
| Solanum triquetrum | Cav. | Solanaceae | 8 |
| Solidago altissima | L. | Asteraceae | 8 |
| Solidago arguta | Aiton | Asteraceae | 8 |
| Solidago auriculata | Shuttlew. ex S.F.Blake | Asteraceae | 8 |
| Solidago caesia | L. | Asteraceae | 8 |
| Solidago canadensis | L. | Asteraceae | 8 |
| Solidago gigantea | Aiton | Asteraceae | 8 |
| Solidago juliae | G.L.Nesom | Asteraceae | 8 |
| Solidago ludoviciana | Small | Asteraceae | 8 |
| Solidago mexicana | L. | Asteraceae | 8 |
| Solidago missouriensis | Nutt. | Asteraceae | 8 |
| Solidago nemoralis | Aiton | Asteraceae | 8 |
| Solidago nitida | Torr. & A.Gray | Asteraceae | 8 |
| Solidago odora | Aiton | Asteraceae | 8 |
| Solidago patula | Muhl. ex Willd. | Asteraceae | 8 |
| Solidago petiolaris | Aiton | Asteraceae | 8 |
| Solidago radula | Nutt. | Asteraceae | 8 |
| Solidago rigida | L. | Asteraceae | 8 |
| Solidago rigidiuscula | (Torr. & A.Gray) Porter | Asteraceae | 8 |
| Solidago rugosa | Mill. | Asteraceae | 8 |
| Solidago tortifolia | Elliott | Asteraceae | 8 |
| Solidago ulmifolia | Muhl. ex Willd. | Asteraceae | 8 |
| Solidago velutina | DC. | Asteraceae | 8 |
| Solidago wrightii | A.Gray | Asteraceae | 8 |
| Sophora nuttalliana | B.L.Turner | Fabaceae | 8 |
| Sophora tomentosa | L. | Fabaceae | 8 |
| Sorghastrum elliottii | (C.Mohr) Nash | Poaceae | 8 |
| Sorghastrum nutans | (L.) Nash | Poaceae | 8 |
| Sotoa confusa | (Garay) Salazar | Orchidaceae | 8 |
| Sparganium americanum | Nutt. | Typhaceae | 8 |
| Spergularia marina | (L.) Besser | Caryophyllaceae | 8 |
| Spermacoce glabra | Michx. | Rubiaceae | 8 |
| Spermacoce remota | Lam. | Rubiaceae | 8 |
| Spermolepis inermis | (Nutt. ex DC.) Mathias & Constance | Apiaceae | 8 |
| Spermolepis lateriflora | G.L.Nesom | Apiaceae | 8 |
| Sphaeralcea coccinea | (Nutt.) Rydb. | Malvaceae | 8 |
| Sphaeralcea digitata | (Greene) Rydb. | Malvaceae | 8 |
| Sphaeralcea fendleri | A.Gray | Malvaceae | 8 |
| Sphaeralcea hastulata | A.Gray | Malvaceae | 8 |
| Sphaeralcea incana | Torr. ex A.Gray | Malvaceae | 8 |
| Sphaeralcea laxa | Wooton & Standl. | Malvaceae | 8 |
| Sphaeralcea leptophylla | (A.Gray) Rydb. | Malvaceae | 8 |
| Sphaeralcea lindheimeri | A.Gray | Malvaceae | 8 |
| Sphaeralcea pedatifida | (A.Gray) A.Gray | Malvaceae | 8 |
| Sphaeralcea polychroma | La Duke | Malvaceae | 8 |
| Sphenopholis filiformis | (Chapm.) Scribn. | Poaceae | 8 |
| Sphenopholis intermedia | (Rydb.) Rydb. | Poaceae | 8 |
| Sphenopholis interrupta | (Buckley) Scribn. | Poaceae | 8 |
| Sphenopholis nitida | (Biehler) Scribn. | Poaceae | 8 |
| Sphenopholis obtusata | (Michx.) Scribn. | Poaceae | 8 |
| Spigelia hedyotidea | A.DC. | Loganiaceae | 8 |
| Spigelia marilandica | (L.) L. | Loganiaceae | 8 |
| Spigelia texana | (Torr. & A.Gray) A.DC. | Loganiaceae | 8 |
| Spiranthes cernua | (L.) Rich. | Orchidaceae | 8 |
| Spiranthes lacera | (Raf.) Raf. | Orchidaceae | 8 |
| Spiranthes laciniata | (Small) Ames | Orchidaceae | 8 |
| Spiranthes longilabris | Lindl. | Orchidaceae | 8 |
| Spiranthes magnicamporum | Sheviak | Orchidaceae | 8 |
| Spiranthes odorata | (Nutt.) Lindl. | Orchidaceae | 8 |
| Spiranthes ovalis | Lindl. | Orchidaceae | 8 |
| Spiranthes praecox | (Walter) S.Watson | Orchidaceae | 8 |
| Spiranthes tuberosa | Raf. | Orchidaceae | 8 |
| Spiranthes vernalis | Engelm. & A.Gray | Orchidaceae | 8 |
| Spirodela polyrhiza | (L.) Schleid. | Araceae | 8 |
| Sporobolus airoides | (Torr.) Torr. | Poaceae | 8 |
| Sporobolus alterniflorus | (Loisel.) P.M.Peterson & Saarela | Poaceae | 8 |
| Sporobolus arenicola | P.M.Peterson | Poaceae | 8 |
| Sporobolus bakeri | (Merr.) P.M.Peterson & Saarela | Poaceae | 8 |
| Sporobolus clandestinus | (Biehler) Hitchc. | Poaceae | 8 |
| Sporobolus compositus | (Poir.) Merr. | Poaceae | 8 |
| Sporobolus contractus | Hitchc. | Poaceae | 8 |
| Sporobolus cryptandrus | (Torr.) A.Gray | Poaceae | 8 |
| Sporobolus cynosuroides | (L.) P.M.Peterson & Saarela | Poaceae | 8 |
| Sporobolus flexuosus | (Vasey) Rydb. | Poaceae | 8 |
| Sporobolus giganteus | Nash | Poaceae | 8 |
| Sporobolus indicus | (L.) R.Br. | Poaceae | 8 |
| Sporobolus junceus | (P.Beauv.) Kunth | Poaceae | 8 |
| Sporobolus michauxianus | (Hitchc.) P.M.Peterson & Saarela | Poaceae | 8 |
| Sporobolus nealleyi | Vasey | Poaceae | 8 |
| Sporobolus neglectus | Nash | Poaceae | 8 |
| Sporobolus pumilus | (Roth) P.M.Peterson & Saarela | Poaceae | 8 |
| Sporobolus pyramidatus | (Lam.) Hitchc. | Poaceae | 8 |
| Sporobolus vaginiflorus | (Torr. ex A.Gray) Alph.Wood | Poaceae | 8 |
| Sporobolus wrightii | Scribn. | Poaceae | 8 |
| Stachys agraria | Schltdl. & Cham. | Lamiaceae | 8 |
| Stachys bigelovii | A.Gray | Lamiaceae | 8 |
| Stachys coccinea | Ortega | Lamiaceae | 8 |
| Stachys drummondii | Benth. | Lamiaceae | 8 |
| Stachys tenuifolia | Willd. | Lamiaceae | 8 |
| Stanleya pinnata | (Pursh) Britton | Brassicaceae | 8 |
| Stapfochloa ciliata | (Sw.) P.M.Peterson | Poaceae | 8 |
| Steinchisma hians | (Elliott) Nash | Poaceae | 8 |
| Stellaria cuspidata | D.F.K.Schltdl. | Caryophyllaceae | 8 |
| Stemodia lanata | Ruiz & Pav. ex Benth. | Plantaginaceae | 8 |
| Stenandrium barbatum | Torr. & A.Gray | Acanthaceae | 8 |
| Stenandrium dulce | (Cav.) Nees | Acanthaceae | 8 |
| Stenanthium densum | (Desr.) Zomlefer & Judd | Melanthiaceae | 8 |
| Stenanthium gramineum | (Ker Gawl.) Morong | Melanthiaceae | 8 |
| Stenanthium texanum | (Bush) Sorrie & Weakley | Melanthiaceae | 8 |
| Stenaria nigricans | (Lam.) Terrell | Rubiaceae | 8 |
| Stenaria pooleana | (B.L.Turner) A.M.Powell | Rubiaceae | 8 |
| Stephanomeria exigua | Nutt. | Asteraceae | 8 |
| Stephanomeria pauciflora | (Torr.) A.Nelson | Asteraceae | 8 |
| Stephanomeria thurberi | A.Gray | Asteraceae | 8 |
| Stevia ovata | Willd. | Asteraceae | 8 |
| Stevia serrata | Cav. | Asteraceae | 8 |
| Stevia viscida | Kunth | Asteraceae | 8 |
| Stewartia malacodendron | L. | Theaceae | 8 |
| Stillingia sylvatica | L. | Euphorbiaceae | 8 |
| Stillingia texana | I.M.Johnst. | Euphorbiaceae | 8 |
| Stillingia treculiana | (Müll.Arg.) I.M.Johnst. | Euphorbiaceae | 8 |
| Stokesia laevis | (Hill) Greene | Asteraceae | 8 |
| Streptanthus bracteatus | A.Gray | Brassicaceae | 8 |
| Streptanthus carinatus | Wright ex A.Gray | Brassicaceae | 8 |
| Streptanthus hyacinthoides | Hook. | Brassicaceae | 8 |
| Streptanthus petiolaris | A.Gray | Brassicaceae | 8 |
| Streptanthus platycarpus | A.Gray | Brassicaceae | 8 |
| Strombocarpa cinerascens | A.Gray | Fabaceae | 8 |
| Strombocarpa pubescens | (Benth.) A.Gray | Fabaceae | 8 |
| Strophostyles leiosperma | (Torr. & A.Gray) Piper | Fabaceae | 8 |
| Strophostyles umbellata | (Muhl. ex Willd.) Britton | Fabaceae | 8 |
| Stuckenia pectinata | (L.) Börner | Potamogetonaceae | 8 |
| Stylisma humistrata | (Walter) Chapm. | Convolvulaceae | 8 |
| Stylisma pickeringii | (Torr. ex M.A.Curtis) A.Gray | Convolvulaceae | 8 |
| Stylisma villosa | (Nash) House | Convolvulaceae | 8 |
| Stylocline micropoides | A.Gray | Asteraceae | 8 |
| Stylosanthes biflora | (L.) Britton, Sterns & Poggenb. | Fabaceae | 8 |
| Styphnolobium affine | (Torr. & A.Gray) Walp. | Fabaceae | 8 |
| Styrax americanus | Lam. | Styracaceae | 8 |
| Styrax grandifolius | Aiton | Styracaceae | 8 |
| Styrax platanifolius | Engelm. ex Torr. | Styracaceae | 8 |
| Suaeda calceoliformis | (Hook.) Moq. | Chenopodiaceae | 8 |
| Suaeda linearis | (Elliott) Moq. | Chenopodiaceae | 8 |
| Suaeda nigra | (Raf.) J.F.Macbr. | Chenopodiaceae | 8 |
| Symphoricarpos longiflorus | A.Gray | Caprifoliaceae | 8 |
| Symphoricarpos occidentalis | (R.Br.) Hook. | Caprifoliaceae | 8 |
| Symphoricarpos orbiculatus | Moench | Caprifoliaceae | 8 |
| Symphoricarpos rotundifolius | A.Gray | Caprifoliaceae | 8 |
| Symphyotrichum cordifolium | (L.) G.L.Nesom | Asteraceae | 8 |
| Symphyotrichum drummondii | (Lindl.) G.L.Nesom | Asteraceae | 8 |
| Symphyotrichum dumosum | (L.) G.L.Nesom | Asteraceae | 8 |
| Symphyotrichum ericoides | (L.) G.L.Nesom | Asteraceae | 8 |
| Symphyotrichum eulae | (Shinners) G.L.Nesom | Asteraceae | 8 |
| Symphyotrichum falcatum | (Lindl.) G.L.Nesom | Asteraceae | 8 |
| Symphyotrichum fendleri | (A.Gray) G.L.Nesom | Asteraceae | 8 |
| Symphyotrichum laeve | (L.) Á.Löve & D.Löve | Asteraceae | 8 |
| Symphyotrichum lanceolatum | (Willd.) G.L.Nesom | Asteraceae | 8 |
| Symphyotrichum oblongifolium | (Nutt.) G.L.Nesom | Asteraceae | 8 |
| Symphyotrichum ontarionis | (Wiegand) G.L.Nesom | Asteraceae | 8 |
| Symphyotrichum patens | (Aiton) G.L.Nesom | Asteraceae | 8 |
| Symphyotrichum praealtum | (Poir.) G.L.Nesom | Asteraceae | 8 |
| Symphyotrichum pratense | (Raf.) G.L.Nesom | Asteraceae | 8 |
| Symphyotrichum racemosum | (Elliott) G.L.Nesom | Asteraceae | 8 |
| Symphyotrichum sericeum | (Vent.) G.L.Nesom | Asteraceae | 8 |
| Symphyotrichum tenuifolium | (L.) G.L.Nesom | Asteraceae | 8 |
| Symplocos tinctoria | (L.) L'Hér. | Symplocaceae | 8 |
| Synthlipsis greggii | A.Gray | Brassicaceae | 8 |
| Syringodium filiforme | Kütz. | Cymodoceaceae | 8 |
| Taenidia integerrima | (L.) Drude | Apiaceae | 8 |
| Tagetes micrantha | Cav. | Asteraceae | 8 |
| Talinopsis frutescens | A.Gray | Anacampserotaceae | 8 |
| Talinum aurantiacum | Engelm. | Talinaceae | 8 |
| Talinum paniculatum | (Jacq.) Gaertn. | Talinaceae | 8 |
| Talinum polygaloides | Gillies ex Arn. | Talinaceae | 8 |
| Tamaulipa azurea | (DC.) R.M.King & H.Rob. | Asteraceae | 8 |
| Tarenaya aculeata | (L.) Soares Neto & Roalson | Cleomaceae | 8 |
| Tauschia texana | A.Gray | Apiaceae | 8 |
| Taxodium distichum | (L.) Rich. | Cupressaceae | 8 |
| Tecoma stans | (L.) Juss. | Bignoniaceae | 8 |
| Tectaria heracleifolia | (Willd.) Underw. | Tectariaceae | 8 |
| Tephrosia lindheimeri | A.Gray | Fabaceae | 8 |
| Tephrosia onobrychoides | Nutt. | Fabaceae | 8 |
| Tephrosia potosina | Brandegee | Fabaceae | 8 |
| Tephrosia virginiana | (L.) Pers. | Fabaceae | 8 |
| Tetraclea coulteri | A.Gray | Lamiaceae | 8 |
| Tetragonotheca ludoviciana | A.Gray | Asteraceae | 8 |
| Tetragonotheca repanda | Small | Asteraceae | 8 |
| Tetragonotheca texana | A.Gray & Engelm. | Asteraceae | 8 |
| Tetramerium nervosum | Nees | Acanthaceae | 8 |
| Tetraneuris acaulis | Greene | Asteraceae | 8 |
| Tetraneuris linearifolia | Greene | Asteraceae | 8 |
| Tetraneuris scaposa | (DC.) Greene | Asteraceae | 8 |
| Teucrium canadense | L. | Lamiaceae | 8 |
| Teucrium coahuilanum | B.L.Turner | Lamiaceae | 8 |
| Teucrium depressum | Small | Lamiaceae | 8 |
| Teucrium laciniatum | Torr. | Lamiaceae | 8 |
| Thalassia testudinum | Banks & Sol. ex K.D.Koenig | Hydrocharitaceae | 8 |
| Thalia dealbata | Fraser | Marantaceae | 8 |
| Thalictrum dasycarpum | Fisch., C.A.Mey. & Avé-Lall. | Ranunculaceae | 8 |
| Thalictrum fendleri | Engelm. ex A.Gray | Ranunculaceae | 8 |
| Thalictrum revolutum | DC. | Ranunculaceae | 8 |
| Thalictrum texanum | (E.Hall ex A.Gray) Small | Ranunculaceae | 8 |
| Thaspium barbinode | (Michx.) Nutt. | Apiaceae | 8 |
| Thaspium trifoliatum | (L.) A.Gray | Apiaceae | 8 |
| Thelesperma burridgeanum | S.F.Blake | Asteraceae | 8 |
| Thelesperma filifolium | (Hook.) A.Gray | Asteraceae | 8 |
| Thelesperma flavodiscum | (Shinners) B.L.Turner | Asteraceae | 8 |
| Thelesperma longipes | A.Gray | Asteraceae | 8 |
| Thelesperma megapotamicum | (Spreng.) Kuntze | Asteraceae | 8 |
| Thelesperma nuecense | B.L.Turner | Asteraceae | 8 |
| Thelesperma simplicifolium | (A.Gray) A.Gray | Asteraceae | 8 |
| Thelocactus bicolor | (Galeotti ex Pfeiff.) Britton & Rose | Cactaceae | 8 |
| Thelocactus setispinus | (Engelm.) E.F.Anderson | Cactaceae | 8 |
| Thelypodium integrifolium | (Nutt.) Endl. | Brassicaceae | 8 |
| Thelypodium texanum | (Cory) Rollins | Brassicaceae | 8 |
| Thelypodium wrightii | A.Gray | Brassicaceae | 8 |
| Thelypteris palustris | Schott | Thelypteridaceae | 8 |
| Thurovia triflora | Rose | Asteraceae | 8 |
| Thymophylla acerosa | (DC.) Strother | Asteraceae | 8 |
| Thymophylla micropoides | (DC.) Strother | Asteraceae | 8 |
| Thymophylla pentachaeta | (DC.) Small | Asteraceae | 8 |
| Thymophylla setifolia | Lag. | Asteraceae | 8 |
| Thymophylla tenuiloba | Small | Asteraceae | 8 |
| Thymophylla tephroleuca | (S.F.Blake) Strother | Asteraceae | 8 |
| Thyrsanthella difformis | (Walter) Pichon | Apocynaceae | 8 |
| Tidestromia lanuginosa | (Nutt.) Standl. | Amaranthaceae | 8 |
| Tidestromia suffruticosa | (Torr.) Standl. | Amaranthaceae | 8 |
| Tiedemannia filiformis | (Walter) M.A.Feist & S.R.Downie | Apiaceae | 8 |
| Tilia americana | L. | Malvaceae | 8 |
| Tillandsia baileyi | Rose ex Small | Bromeliaceae | 8 |
| Tillandsia recurvata | (L.) L. | Bromeliaceae | 8 |
| Tillandsia usneoides | (L.) L. | Bromeliaceae | 8 |
| Tinantia anomala | C.B.Clarke | Commelinaceae | 8 |
| Tipularia discolor | (Pursh) Nutt. | Orchidaceae | 8 |
| Tiquilia canescens | (DC.) A.T.Richardson | Ehretiaceae | 8 |
| Tiquilia gossypina | (Wooton & Standl.) A.T.Richardson | Ehretiaceae | 8 |
| Tiquilia greggii | (Torr. & A.Gray) A.T.Richardson | Ehretiaceae | 8 |
| Tiquilia hispidissima | (Torr. & A.Gray) A.T.Richardson | Ehretiaceae | 8 |
| Tomostima cuneifolia | (Nutt. ex Torr. & A.Gray) Al-Shehbaz, M.Koch & Jordon-Thaden | Brassicaceae | 8 |
| Tomostima platycarpa | (Torr. & A.Gray) Al-Shehbaz, M.Koch & Jordon-Thaden | Brassicaceae | 8 |
| Tomostima reptans | (Lam.) Al-Shehbaz, M.Koch & Jordon-Thaden | Brassicaceae | 8 |
| Torreyostellaria jamesiana | (Torr.) Gang Yao, B.Xue & Z.Q.Song | Caryophyllaceae | 8 |
| Townsendia annua | Beaman | Asteraceae | 8 |
| Townsendia exscapa | (Richardson) Porter | Asteraceae | 8 |
| Toxicodendron pubescens | Mill. | Anacardiaceae | 8 |
| Toxicodendron radicans | (L.) Kuntze | Anacardiaceae | 8 |
| Toxicodendron vernix | Kuntze | Anacardiaceae | 8 |
| Toxicoscordion nuttallii | (A.Gray) Rydb. | Melanthiaceae | 8 |
| Trachypogon spicatus | (L.f.) Kuntze | Poaceae | 8 |
| Tradescantia brevifolia | Rose | Commelinaceae | 8 |
| Tradescantia crassifolia | Cav. | Commelinaceae | 8 |
| Tradescantia edwardsiana | Tharp | Commelinaceae | 8 |
| Tradescantia gigantea | Rose | Commelinaceae | 8 |
| Tradescantia hirsutiflora | Bush | Commelinaceae | 8 |
| Tradescantia occidentalis | (Britton) Smyth | Commelinaceae | 8 |
| Tradescantia ohiensis | Raf. | Commelinaceae | 8 |
| Tradescantia pedicellata | Celarier | Commelinaceae | 8 |
| Tradescantia reverchonii | Bush | Commelinaceae | 8 |
| Tradescantia subacaulis | Bush | Commelinaceae | 8 |
| Tradescantia tharpii | E.S.Anderson & Woodson | Commelinaceae | 8 |
| Tradescantia wrightii | Rose & Bush | Commelinaceae | 8 |
| Tragia amblyodonta | (Müll.Arg.) Pax & K.Hoffm. | Euphorbiaceae | 8 |
| Tragia betonicifolia | Nutt. | Euphorbiaceae | 8 |
| Tragia brevispica | Engelm. & A.Gray | Euphorbiaceae | 8 |
| Tragia cordata | Michx. | Euphorbiaceae | 8 |
| Tragia glanduligera | Pax & K.Hoffm. | Euphorbiaceae | 8 |
| Tragia leptophylla | (Torr.) I.M.Johnst. | Euphorbiaceae | 8 |
| Tragia nigricans | Bush | Euphorbiaceae | 8 |
| Tragia ramosa | Torr. | Euphorbiaceae | 8 |
| Tragia smallii | Shinners | Euphorbiaceae | 8 |
| Tragia urens | L. | Euphorbiaceae | 8 |
| Tragia urticifolia | Michx. | Euphorbiaceae | 8 |
| Trautvetteria caroliniensis | (Walter) Vail | Ranunculaceae | 8 |
| Trepocarpus aethusae | Nutt. ex DC. | Apiaceae | 8 |
| Triantha racemosa | (Walter) Small | Tofieldiaceae | 8 |
| Trianthema portulacastrum | L. | Aizoaceae | 8 |
| Trichogalium bermudense | (L.) Kadereit & Schneew. | Rubiaceae | 8 |
| Trichogalium boreale | (L.) Fourr. | Rubiaceae | 8 |
| Trichogalium circaezans | (Michx.) Kadereit & Schneew. | Rubiaceae | 8 |
| Trichostema arizonicum | A.Gray | Lamiaceae | 8 |
| Trichostema dichotomum | L. | Lamiaceae | 8 |
| Trichostema setaceum | Houtt. | Lamiaceae | 8 |
| Tridens albescens | (Vasey) Wooton & Standl. | Poaceae | 8 |
| Tridens ambiguus | (Elliott) Schult. | Poaceae | 8 |
| Tridens chapmanii | (Small) Chase | Poaceae | 8 |
| Tridens congestus | (L.H.Dewey) Nash | Poaceae | 8 |
| Tridens flavus | (L.) Hitchc. | Poaceae | 8 |
| Tridens strictus | (Nutt.) Nash | Poaceae | 8 |
| Tridens texanus | (S.Watson) Nash | Poaceae | 8 |
| Tridentopsis buckleyana | (L.H.Dewey) P.M.Peterson & Romasch. | Poaceae | 8 |
| Tridentopsis mutica | (Torr.) P.M.Peterson | Poaceae | 8 |
| Trifolium bejariense | Moric. | Fabaceae | 8 |
| Trifolium reflexum | L. | Fabaceae | 8 |
| Triglochin maritima | L. | Juncaginaceae | 8 |
| Trillium gracile | J.D.Freeman | Melanthiaceae | 8 |
| Trillium recurvatum | L.C.Beck | Melanthiaceae | 8 |
| Trillium texanum | Buckley | Melanthiaceae | 8 |
| Trillium viridescens | Nutt. | Melanthiaceae | 8 |
| Triodanis coloradoensis | (Buckley) McVaugh | Campanulaceae | 8 |
| Triodanis holzingeri | McVaugh | Campanulaceae | 8 |
| Triodanis lamprosperma | McVaugh | Campanulaceae | 8 |
| Triodanis leptocarpa | Nieuwl. | Campanulaceae | 8 |
| Triodanis perfoliata | (L.) Nieuwl. | Campanulaceae | 8 |
| Triodanis texana | McVaugh | Campanulaceae | 8 |
| Triosteum angustifolium | L. | Caprifoliaceae | 8 |
| Triosteum perfoliatum | L. | Caprifoliaceae | 8 |
| Triphora trianthophoros | (Sw.) Rydb. | Orchidaceae | 8 |
| Triplasiella eragrostoides | (Vasey & Scribn.) P.M.Peterson & Romasch. | Poaceae | 8 |
| Triplasis purpurea | (Walter) Chapm. | Poaceae | 8 |
| Tripogonella spicata | (Nees) P.M.Peterson & Romasch. | Poaceae | 8 |
| Tripsacum dactyloides | (L.) L. | Poaceae | 8 |
| Trixis californica | Kellogg | Asteraceae | 8 |
| Trixis inula | Crantz | Asteraceae | 8 |
| Turnera coerulea | Sessé & Moc. ex DC. | Passifloraceae | 8 |
| Turnera diffusa | Willd. ex Schult. | Passifloraceae | 8 |
| Typha domingensis | Pers. | Typhaceae | 8 |
| Typha latifolia | L. | Typhaceae | 8 |
| Ulmus alata | Michx. | Ulmaceae | 8 |
| Ulmus americana | L. | Ulmaceae | 8 |
| Ulmus crassifolia | Nutt. | Ulmaceae | 8 |
| Ulmus rubra | Muhl. | Ulmaceae | 8 |
| Ungnadia speciosa | Endl. | Sapindaceae | 8 |
| Uniola paniculata | L. | Poaceae | 8 |
| Urochloa arizonica | (Scribn. & Merr.) Morrone & Zuloaga | Poaceae | 8 |
| Urochloa ciliatissima | (Buckley) R.D.Webster | Poaceae | 8 |
| Urochloa platyphylla | (Munro ex C.Wright) R.D.Webster | Poaceae | 8 |
| Uropappus lindleyi | (DC.) Nutt. | Asteraceae | 8 |
| Urtica chamaedryoides | Pursh | Urticaceae | 8 |
| Urtica gracilenta | Greene | Urticaceae | 8 |
| Urtica gracilis | Aiton | Urticaceae | 8 |
| Urvillea ulmacea | Kunth | Sapindaceae | 8 |
| Utricularia cornuta | Michx. | Lentibulariaceae | 8 |
| Utricularia foliosa | L. | Lentibulariaceae | 8 |
| Utricularia gibba | L. | Lentibulariaceae | 8 |
| Utricularia inflata | Walter | Lentibulariaceae | 8 |
| Utricularia juncea | Vahl | Lentibulariaceae | 8 |
| Utricularia macrorhiza | Leconte | Lentibulariaceae | 8 |
| Utricularia purpurea | Walter | Lentibulariaceae | 8 |
| Utricularia radiata | Small | Lentibulariaceae | 8 |
| Utricularia striata | Leconte ex Torr. | Lentibulariaceae | 8 |
| Utricularia subulata | L. | Lentibulariaceae | 8 |
| Uvularia perfoliata | L. | Colchicaceae | 8 |
| Uvularia sessilifolia | L. | Colchicaceae | 8 |
| Vaccinium arboreum | Marshall | Ericaceae | 8 |
| Vaccinium corymbosum | L. | Ericaceae | 8 |
| Vaccinium stamineum | L. | Ericaceae | 8 |
| Vachellia bravoensis | (Isely) Seigler & Ebinger | Fabaceae | 8 |
| Vachellia constricta | (Benth.) Seigler & Ebinger | Fabaceae | 8 |
| Vachellia farnesiana | (L.) Wight & Arn. | Fabaceae | 8 |
| Vachellia rigidula | (Benth.) Seigler & Ebinger | Fabaceae | 8 |
| Vachellia schaffneri | (S.Watson) Seigler & Ebinger | Fabaceae | 8 |
| Vachellia vernicosa | (Britton & Rose) Seigler & Ebinger | Fabaceae | 8 |
| Valeriana amarella | (Lindh. ex Engelm.) Christenh. & Byng | Caprifoliaceae | 8 |
| Valeriana arizonica | A.Gray | Caprifoliaceae | 8 |
| Valeriana edwardsensis | Christenh. & Byng | Caprifoliaceae | 8 |
| Varilla texana | A.Gray | Asteraceae | 8 |
| Verbena bipinnatifida | (Nutt.) Schauer | Verbenaceae | 8 |
| Verbena bracteata | Cav. ex Lag. & Rodr. | Verbenaceae | 8 |
| Verbena canadensis | (L.) Britton | Verbenaceae | 8 |
| Verbena canescens | Kunth | Verbenaceae | 8 |
| Verbena carnea | Medik. | Verbenaceae | 8 |
| Verbena elegans | Kunth | Verbenaceae | 8 |
| Verbena halei | Small | Verbenaceae | 8 |
| Verbena hastata | L. | Verbenaceae | 8 |
| Verbena macdougalii | A.Heller | Verbenaceae | 8 |
| Verbena menthifolia | Benth. | Verbenaceae | 8 |
| Verbena neomexicana | (A.Gray) Briq. | Verbenaceae | 8 |
| Verbena perennis | Wooton | Verbenaceae | 8 |
| Verbena plicata | Greene | Verbenaceae | 8 |
| Verbena polyantha | (Umber) Moldenke | Verbenaceae | 8 |
| Verbena pumila | Rydb. | Verbenaceae | 8 |
| Verbena quadrangulata | A.Heller | Verbenaceae | 8 |
| Verbena racemosa | Eggert | Verbenaceae | 8 |
| Verbena scabra | Vahl | Verbenaceae | 8 |
| Verbena stricta | Vent. | Verbenaceae | 8 |
| Verbena tumidula | L.M.Perry | Verbenaceae | 8 |
| Verbena urticifolia | L. | Verbenaceae | 8 |
| Verbena xutha | Lehm. | Verbenaceae | 8 |
| Verbesina alternifolia | (L.) Britton ex Kearney | Asteraceae | 8 |
| Verbesina helianthoides | Michx. | Asteraceae | 8 |
| Verbesina lindheimeri | B.L.Rob. & Greenm. | Asteraceae | 8 |
| Verbesina microptera | DC. | Asteraceae | 8 |
| Verbesina occidentalis | Walter | Asteraceae | 8 |
| Verbesina virginica | L. | Asteraceae | 8 |
| Verbesina walteri | Shinners | Asteraceae | 8 |
| Vernonia baldwinii | Torr. | Asteraceae | 8 |
| Vernonia gigantea | (Walter) Trel. | Asteraceae | 8 |
| Vernonia lindheimeri | A.Gray & Engelm. | Asteraceae | 8 |
| Vernonia missurica | Raf. | Asteraceae | 8 |
| Vernonia texana | Small | Asteraceae | 8 |
| Veronica americana | (Raf.) Schwein. ex Benth. | Plantaginaceae | 8 |
| Veronica catenata | Pennell | Plantaginaceae | 8 |
| Veronica peregrina | L. | Plantaginaceae | 8 |
| Veronicastrum virginicum | (L.) Farw. | Plantaginaceae | 8 |
| Vesper bulbosus | (A.Nelson) R.L.Hartm. & G.L.Nesom | Apiaceae | 8 |
| Vesper macrorhizus | (Buckley) R.L.Hartm. & G.L.Nesom | Apiaceae | 8 |
| Vesper montanus | (Torr. & A.Gray) R.L.Hartm. & G.L.Nesom | Apiaceae | 8 |
| Viburnum acerifolium | L. | Viburnaceae | 8 |
| Viburnum cassinoides | L. | Viburnaceae | 8 |
| Viburnum nudum | L. | Viburnaceae | 8 |
| Viburnum prunifolium | L. | Viburnaceae | 8 |
| Viburnum rafinesqueanum | Schult. | Viburnaceae | 8 |
| Viburnum rufidulum | Raf. | Viburnaceae | 8 |
| Viburnum scabrellum | (Torr. & A.Gray) Chapm. | Viburnaceae | 8 |
| Vicia americana | Muhl. ex Willd. | Fabaceae | 8 |
| Vicia caroliniana | Walter | Fabaceae | 8 |
| Vicia ludoviciana | Nutt. | Fabaceae | 8 |
| Vicia minutiflora | D.Dietr. | Fabaceae | 8 |
| Vigna luteola | (Jacq.) Benth. | Fabaceae | 8 |
| Viguiera dentata | (Cav.) Spreng. | Asteraceae | 8 |
| Viola lanceolata | L. | Violaceae | 8 |
| Viola missouriensis | Greene | Violaceae | 8 |
| Viola nephrophylla | Greene | Violaceae | 8 |
| Viola palmata | L. | Violaceae | 8 |
| Viola pedata | L. | Violaceae | 8 |
| Viola primulifolia | L. | Violaceae | 8 |
| Viola pubescens | Aiton | Violaceae | 8 |
| Viola rafinesquei | Greene | Violaceae | 8 |
| Viola sagittata | Aiton | Violaceae | 8 |
| Viola sororia | Willd. | Violaceae | 8 |
| Viola villosa | Walter | Violaceae | 8 |
| Viola walteri | House | Violaceae | 8 |
| Vitis acerifolia | Raf. | Vitaceae | 8 |
| Vitis aestivalis | Michx. | Vitaceae | 8 |
| Vitis arizonica | Engelm. | Vitaceae | 8 |
| Vitis berlandieri | Planch. | Vitaceae | 8 |
| Vitis cinerea | (Engelm.) Millardet | Vitaceae | 8 |
| Vitis monticola | Buckley | Vitaceae | 8 |
| Vitis mustangensis | Buckley | Vitaceae | 8 |
| Vitis palmata | Vahl | Vitaceae | 8 |
| Vitis riparia | Michx. | Vitaceae | 8 |
| Vitis rotundifolia | Michx. | Vitaceae | 8 |
| Vitis rupestris | Scheele | Vitaceae | 8 |
| Vitis vulpina | L. | Vitaceae | 8 |
| Waltheria indica | L. | Malvaceae | 8 |
| Wedelia acapulcensis | Kunth | Asteraceae | 8 |
| Wisteria frutescens | (L.) Poir. | Fabaceae | 8 |
| Wolffia brasiliensis | Wedd. | Araceae | 8 |
| Wolffia columbiana | H.Karst. | Araceae | 8 |
| Wolffiella gladiata | (Hegelm.) Hegelm. | Araceae | 8 |
| Woodsia neomexicana | Windham | Woodsiaceae | 8 |
| Woodsia obtusa | (Sw.) Torr. | Woodsiaceae | 8 |
| Woodsia phillipsii | Windham | Woodsiaceae | 8 |
| Xanthisma gracile | (Nutt.) D.R.Morgan & R.L.Hartm. | Asteraceae | 8 |
| Xanthisma spinulosum | (Pursh) D.R.Morgan & R.L.Hartm. | Asteraceae | 8 |
| Xanthisma viscidum | (Wooton & Standl.) D.R.Morgan & R.L.Hartm. | Asteraceae | 8 |
| Xanthium orientale | L. | Asteraceae | 8 |
| Xanthium spinosum | L. | Asteraceae | 8 |
| Xanthocephalum gymnospermoides | (A.Gray) Benth. & Hook.f. | Asteraceae | 8 |
| Xanthorhiza simplicissima | Marshall | Ranunculaceae | 8 |
| Xylorhiza wrightii | Greene | Asteraceae | 8 |
| Xylosma flexuosa | (Kunth) Hemsl. | Salicaceae | 8 |
| Xyris ambigua | Beyr. ex Kunth | Xyridaceae | 8 |
| Xyris baldwiniana | Schult. | Xyridaceae | 8 |
| Xyris caroliniana | Walter | Xyridaceae | 8 |
| Xyris difformis | Chapm. | Xyridaceae | 8 |
| Xyris fimbriata | Elliott | Xyridaceae | 8 |
| Xyris jupicai | Rich. | Xyridaceae | 8 |
| Xyris platylepis | Chapm. | Xyridaceae | 8 |
| Xyris smalliana | Nash | Xyridaceae | 8 |
| Xyris stricta | Chapm. | Xyridaceae | 8 |
| Xyris torta | Sm. | Xyridaceae | 8 |
| Yeatesia viridiflora | (Nees) Small | Acanthaceae | 8 |
| Yucca aloifolia | L. | Asparagaceae | 8 |
| Yucca arkansana | Trel. | Asparagaceae | 8 |
| Yucca baccata | Torr. | Asparagaceae | 8 |
| Yucca campestris | McKelvey | Asparagaceae | 8 |
| Yucca cernua | E.L.Keith | Asparagaceae | 8 |
| Yucca constricta | Buckley | Asparagaceae | 8 |
| Yucca elata | (Engelm.) Engelm. | Asparagaceae | 8 |
| Yucca faxoniana | (Trel.) Sarg. | Asparagaceae | 8 |
| Yucca flaccida | Haw. | Asparagaceae | 8 |
| Yucca glauca | Nutt. | Asparagaceae | 8 |
| Yucca necopina | Shinners | Asparagaceae | 8 |
| Yucca pallida | McKelvey | Asparagaceae | 8 |
| Yucca reverchonii | Trel. | Asparagaceae | 8 |
| Yucca rostrata | Engelm. ex Trel. | Asparagaceae | 8 |
| Yucca rupicola | Scheele | Asparagaceae | 8 |
| Yucca thompsoniana | Trel. | Asparagaceae | 8 |
| Zannichellia palustris | L. | Potamogetonaceae | 8 |
| Zanthoxylum americanum | Mill. | Rutaceae | 8 |
| Zanthoxylum clava-herculis | L. | Rutaceae | 8 |
| Zanthoxylum fagara | Sarg. | Rutaceae | 8 |
| Zeltnera arizonica | (A.Gray) G.Mans. | Gentianaceae | 8 |
| Zeltnera beyrichii | (Torr.) G.Mans. | Gentianaceae | 8 |
| Zeltnera calycosa | (Buckley) G.Mans. | Gentianaceae | 8 |
| Zeltnera maryanniana | (B.L.Turner) G.Mans. | Gentianaceae | 8 |
| Zeltnera texensis | (Griseb.) G.Mans. ex J.S.Pringle | Gentianaceae | 8 |
| Zephyranthes chlorosolen | (Herb.) D.Dietr. | Amaryllidaceae | 8 |
| Zephyranthes drummondii | D.Don | Amaryllidaceae | 8 |
| Zephyranthes pulchella | J.G.Sm. | Amaryllidaceae | 8 |
| Zinnia acerosa | (DC.) A.Gray | Asteraceae | 8 |
| Zinnia grandiflora | Nutt. | Asteraceae | 8 |
| Zizania texana | Hitchc. | Poaceae | 8 |
| Zizaniopsis miliacea | (Michx.) Döll & Asch. | Poaceae | 8 |
| Zornia bracteata | J.F.Gmel. | Fabaceae | 8 |
| Zornia latifolia | Sm. | Fabaceae | 8 |
| Zuloagaea bulbosa | (Kunth) Bess | Poaceae | 8 |
| Allium perdulce | S.V.Fraser | Amaryllidaceae | 7 |
| Arcytophyllum fasciculatum | (A.Gray) Terrell & H.Rob. | Rubiaceae | 7 |
| Astragalus giganteus | S.Watson | Fabaceae | 7 |
| Astragalus pictiformis | Barneby | Fabaceae | 7 |
| Baccharis bigelovii | A.Gray | Asteraceae | 7 |
| Blepharidachne bigelovii | (S.Watson) Hack. | Poaceae | 7 |
| Boerhavia ciliata | Brandegee | Nyctaginaceae | 7 |
| Boerhavia spicata | Choisy | Nyctaginaceae | 7 |
| Brickellia brachyphylla | (A.Gray) A.Gray | Asteraceae | 7 |
| Carex floridana | Schwein. | Cyperaceae | 7 |
| Christella hispidula | (Decne.) Holttum | Thelypteridaceae | 7 |
| Corispermum americanum | (Nutt.) Nutt. | Chenopodiaceae | 7 |
| Crataegus reverchonii | Sarg. | Rosaceae | 7 |
| Crepis runcinata | (E.James) Torr. & A.Gray | Asteraceae | 7 |
| Cyperus hortensis | (Salzm. ex Steud.) Dorr | Cyperaceae | 7 |
| Dalea austrotexana | B.L.Turner | Fabaceae | 7 |
| Desmanthus obtusus | S.Watson | Fabaceae | 7 |
| Didiplis diandra | (Nutt. ex DC.) Alph.Wood | Lythraceae | 7 |
| Drymaria pachyphylla | Wooton & Standl. | Caryophyllaceae | 7 |
| Echinocereus dasyacanthus | Engelm. | Cactaceae | 7 |
| Echinocereus davisii | Houghton | Cactaceae | 7 |
| Eleocharis brittonii | Svenson ex Small | Cyperaceae | 7 |
| Eleocharis vivipara | Link | Cyperaceae | 7 |
| Elionurus barbiculmis | Hack. ex Scribn. | Poaceae | 7 |
| Eriochloa acuminata | (J.Presl) Kunth | Poaceae | 7 |
| Festuca sciurea | Nutt. | Poaceae | 7 |
| Flyriella parryi | (A.Gray) R.M.King & H.Rob. | Asteraceae | 7 |
| Frangula betulifolia | (Greene) Grubov | Rhamnaceae | 7 |
| Gamochaeta antillana | (Urb.) Anderb. | Asteraceae | 7 |
| Glyceria arkansana | Fernald | Poaceae | 7 |
| Gomphrena nitida | Rothr. | Amaranthaceae | 7 |
| Grindelia oolepis | S.F.Blake | Asteraceae | 7 |
| Helianthus paradoxus | Heiser | Asteraceae | 7 |
| Hygrophila costata | Nees | Acanthaceae | 7 |
| Isoetes melanopoda | J.Gay & Durieu | Isoetaceae | 7 |
| Liatris tenuis | Shinners | Asteraceae | 7 |
| Linanthus bigelovii | (A.Gray) Greene | Polemoniaceae | 7 |
| Monarda lindheimeri | Engelm. & A.Gray | Lamiaceae | 7 |
| Muhlenbergia villiflora | Hitchc. | Poaceae | 7 |
| Nicolletia edwardsii | A.Gray | Asteraceae | 7 |
| Ophioglossum nudicaule | L.f. | Ophioglossaceae | 7 |
| Paepalanthus digynus | (Körn.) Christenh. & Byng | Eriocaulaceae | 7 |
| Palafoxia reverchonii | (Bush) Cory | Asteraceae | 7 |
| Paronychia wilkinsonii | S.Watson | Caryophyllaceae | 7 |
| Parthenium argentatum | A.Gray | Asteraceae | 7 |
| Pelecyphora minima | (Baird) D.Aquino & Dan.Sánchez | Cactaceae | 7 |
| Persicaria meisneriana | (Cham. & Schltdl.) M.Gómez | Polygonaceae | 7 |
| Physostegia correllii | (Lundell) Shinners | Lamiaceae | 7 |
| Physostegia longisepala | P.D.Cantino | Lamiaceae | 7 |
| Pseudognaphalium viscosum | (Kunth) Anderb. | Asteraceae | 7 |
| Pyrrhopappus grandiflorus | (Nutt.) Nutt. | Asteraceae | 7 |
| Sabulina muscorum | (Fassett) E.E.Schill. | Caryophyllaceae | 7 |
| Sageretia wrightii | S.Watson | Rhamnaceae | 7 |
| Salvia pentstemonoides | Kunth & C.D.Bouché | Lamiaceae | 7 |
| Salvia summa | A.Nelson | Lamiaceae | 7 |
| Salvia whitehousei | Alziar | Lamiaceae | 7 |
| Scirpus pallidus | (Britton) Fernald | Cyperaceae | 7 |
| Senecio riddellii | Torr. & A.Gray | Asteraceae | 7 |
| Sida neomexicana | A.Gray | Malvaceae | 7 |
| Spermolepis divaricata | (Walter) Raf. | Apiaceae | 7 |
| Suaeda tampicensis | (Standl.) Standl. | Chenopodiaceae | 7 |
| Townsendia texensis | Larsen | Asteraceae | 7 |
| Tradescantia humilis | Rose | Commelinaceae | 7 |
| Trichocoronis wrightii | A.Gray | Asteraceae | 7 |
| Acleisanthes crassifolia | A.Gray | Nyctaginaceae | 6 |
| Agalinis navasotensis | Dubrule & Canne-Hill. | Orobanchaceae | 6 |
| Agastache breviflora | (A.Gray) Epling | Lamiaceae | 6 |
| Agave gracilipes | Trel. | Asparagaceae | 6 |
| Amaranthus arenicola | I.M.Johnst. | Amaranthaceae | 6 |
| Antiphytum heliotropioides | A.DC. | Boraginaceae | 6 |
| Aristida basiramea | Vasey | Poaceae | 6 |
| Atriplex cristata | Humb. & Bonpl. ex Willd. | Chenopodiaceae | 6 |
| Baccharis sulcata | DC. | Asteraceae | 6 |
| Bacopa rotundifolia | (Michx.) Wettst. | Plantaginaceae | 6 |
| Blanchardia clypeata | (L.) M.M.Hanes & R.L.Barrett | Malvaceae | 6 |
| Bradburia hirtella | Torr. & A.Gray | Asteraceae | 6 |
| Cakile geniculata | (B.L.Rob.) Millsp. | Brassicaceae | 6 |
| Calystegia macounii | (Greene) Brummitt | Convolvulaceae | 6 |
| Carex alata | Torr. | Cyperaceae | 6 |
| Cirsium turneri | Warnock | Asteraceae | 6 |
| Descurainia adenophora | (Wooton & Standl.) O.E.Schulz | Brassicaceae | 6 |
| Echinocactus horizonthalonius | Lem. | Cactaceae | 6 |
| Eleocharis occulta | S.G.Sm. | Cyperaceae | 6 |
| Eragrostis capillaris | (L.) Nees | Poaceae | 6 |
| Eragrostis frankii | Steud. | Poaceae | 6 |
| Euploca fruticosa | (L.) J.I.M.Melo & Semir | Heliotropiaceae | 6 |
| Flaveria campestris | J.R.Johnst. | Asteraceae | 6 |
| Gaillardia coahuilensis | B.L.Turner | Asteraceae | 6 |
| Grindelia arizonica | A.Gray | Asteraceae | 6 |
| Hackelia besseyi | (Rydb.) J.L.Gentry | Boraginaceae | 6 |
| Houstonia subviscosa | (C.Wright ex A.Gray) A.Gray | Rubiaceae | 6 |
| Hymenoxys texana | Cockerell | Asteraceae | 6 |
| Imperata brevifolia | Vasey | Poaceae | 6 |
| Ipomoea edwardsensis | (O'Kennon & G.L.Nesom) O'Kennon | Convolvulaceae | 6 |
| Mammillaria prolifera | (Mill.) Haw. | Cactaceae | 6 |
| Marsilea mollis | B.L.Rob. & Fernald | Marsileaceae | 6 |
| Mentzelia reverchonii | (Urb. & Gilg) H.J.Thomps. & Zavort. | Loasaceae | 6 |
| Metastelma pringlei | A.Gray | Apocynaceae | 6 |
| Microchloa kunthii | Desv. | Poaceae | 6 |
| Mimosa hystricina | (Small ex Britton & Rose) B.L.Turner | Fabaceae | 6 |
| Mimosa latidens | (Small) B.L.Turner | Fabaceae | 6 |
| Monarda stanfieldii | Small | Lamiaceae | 6 |
| Muhlenbergia sobolifera | (Muhl. ex Willd.) Trin. | Poaceae | 6 |
| Notholaena greggii | (Mett. ex Kuhn) Maxon | Pteridaceae | 6 |
| Oenothera heterophylla | Spach | Onagraceae | 6 |
| Oenothera spachiana | Torr. & A.Gray | Onagraceae | 6 |
| Oreocarya paysonii | J.F.Macbr. | Boraginaceae | 6 |
| Pauciflora sagittifolia | (A.Gray) Morillo, Liede & Meve | Apocynaceae | 6 |
| Pediomelum reverchonii | (S.Watson) Rydb. | Fabaceae | 6 |
| Pelecyphora sneedii | (Britton & Rose) D.Aquino & Dan.Sánchez | Cactaceae | 6 |
| Phalaris angusta | Nees ex Trin. | Poaceae | 6 |
| Plantago pusilla | Nutt. | Plantaginaceae | 6 |
| Polygonum ramosissimum | Michx. | Polygonaceae | 6 |
| Rhinotropis rimulicola | (Steyerm.) J.R.Abbott | Polygalaceae | 6 |
| Selaginella viridissima | Weath. | Selaginellaceae | 6 |
| Senna orcuttii | (Britton & Rose) H.S.Irwin & Barneby | Fabaceae | 6 |
| Seymeria bipinnatisecta | Seem. | Orobanchaceae | 6 |
| Sparganium androcladum | (Engelm.) Morong | Typhaceae | 6 |
| Sporobolus purpurascens | (Sw.) Ham. | Poaceae | 6 |
| Tetraneuris turneri | (K.F.Parker) K.F.Parker | Asteraceae | 6 |
| Trichoneura elegans | Swallen | Poaceae | 6 |
| Woodsia plummerae | Lemmon | Woodsiaceae | 6 |
| Zapoteca media | (M.Martens & Galeotti) H.M.Hern. | Fabaceae | 6 |
| Zephyranthes jonesii | (Cory) Traub | Amaryllidaceae | 6 |
| Abutilon hulseanum | (Torr. & A.Gray) Torr. ex Baker f. | Malvaceae | 5 |
| Aristida havardii | Vasey | Poaceae | 5 |
| Aristida schiedeana | Trin. & Rupr. | Poaceae | 5 |
| Bothriochloa springfieldii | (Gould) Parodi | Poaceae | 5 |
| Castilleja rigida | Eastw. | Orobanchaceae | 5 |
| Chenopodium neomexicanum | Standl. | Chenopodiaceae | 5 |
| Cleomella angustifolia | Torr. | Cleomaceae | 5 |
| Cuscuta chinensis | Lam. | Convolvulaceae | 5 |
| Cyperus reflexus | Vahl | Cyperaceae | 5 |
| Dichaetophora campestris | A.Gray | Asteraceae | 5 |
| Digitaria pubiflora | (Vasey) Wipff | Poaceae | 5 |
| Eleocharis flavescens | (Poir.) Urb. | Cyperaceae | 5 |
| Eleocharis microcarpa | Torr. | Cyperaceae | 5 |
| Elymus arizonicus | (Scribn. & J.G.Sm.) Gould | Poaceae | 5 |
| Eriogonum correllii | Reveal | Polygonaceae | 5 |
| Euphorbia bilobata | Engelm. | Euphorbiaceae | 5 |
| Festuca ligulata | Swallen | Poaceae | 5 |
| Fimbristylis decipiens | Kral | Cyperaceae | 5 |
| Flaveria chlorifolia | A.Gray | Asteraceae | 5 |
| Grusonia densispina | (Ralston & Hilsenb.) Pinkava | Cactaceae | 5 |
| Heteranthera mexicana | S.Watson | Pontederiaceae | 5 |
| Liatris bracteata | Gaiser | Asteraceae | 5 |
| Mimosa rupertiana | B.L.Turner | Fabaceae | 5 |
| Monarda viridissima | Correll | Lamiaceae | 5 |
| Mostacillastrum purpusii | (Brandegee) Al-Shehbaz | Brassicaceae | 5 |
| Muhlenbergia andina | (Nutt.) Hitchc. | Poaceae | 5 |
| Muhlenbergia dubia | E.Fourn. | Poaceae | 5 |
| Nama torynophylla | Greenm. | Namaceae | 5 |
| Notholaena grayi | Davenp. | Pteridaceae | 5 |
| Notholaena neglecta | Maxon | Pteridaceae | 5 |
| Oenothera hispida | (Benth.) W.L.Wagner, Hoch & Zarucchi | Onagraceae | 5 |
| Opuntia nemoralis | Griffiths | Cactaceae | 5 |
| Panicum philadelphicum | Bernh. ex Nees | Poaceae | 5 |
| Paysonia lasiocarpa | (Hook. ex A.Gray) O'Kane & Al-Shehbaz | Brassicaceae | 5 |
| Persicaria hispida | (Kunth) M.Gómez | Polygonaceae | 5 |
| Pseudabutilon umbellatum | (L.) Fryxell | Malvaceae | 5 |
| Pseudoclappia arenaria | Rydb. | Asteraceae | 5 |
| Pseudoclappia watsonii | A.M.Powell & B.L.Turner | Asteraceae | 5 |
| Psilactis brevilingulata | Sch.Bip. ex Hemsl. | Asteraceae | 5 |
| Quercus boyntonii | Beadle | Fagaceae | 5 |
| Rhynchospora scirpoides | (Torr.) Griseb. | Cyperaceae | 5 |
| Sabatia arenicola | Greenm. | Gentianaceae | 5 |
| Schiedeella arizonica | P.M.Br. | Orchidaceae | 5 |
| Scutellaria resinosa | Torr. | Lamiaceae | 5 |
| Sedum havardii | Rose | Crassulaceae | 5 |
| Seymeria scabra | A.Gray | Orobanchaceae | 5 |
| Suaeda conferta | (Small) I.M.Johnst. | Chenopodiaceae | 5 |
| Vaseyochloa multinervosa | (Vasey) Hitchc. | Poaceae | 5 |
| Verbena cloverae | Moldenke | Verbenaceae | 5 |
| Zephyranthes traubii | (Hayward) Moldenke | Amaryllidaceae | 5 |
| Acleisanthes parvifolia | (Torr.) R.A.Levin | Nyctaginaceae | 4 |
| Agave sileri | (Verh.-Will.) Thiede & Eggli | Asparagaceae | 4 |
| Astragalus albulus | Wooton & Standl. | Fabaceae | 4 |
| Bouteloua simplex | Lag. | Poaceae | 4 |
| Brazoria enquistii | M.W.Turner | Lamiaceae | 4 |
| Brickellia lemmonii | A.Gray | Asteraceae | 4 |
| Brickellia venosa | B.L.Rob. | Asteraceae | 4 |
| Chaetopappa parryi | A.Gray | Asteraceae | 4 |
| Chthamalia atrostellata | (Rintz) Morillo | Apocynaceae | 4 |
| Crataegus greggiana | Eggl. | Rosaceae | 4 |
| Crataegus venusta | Beadle | Rosaceae | 4 |
| Croton sancti-lazari | Croizat | Euphorbiaceae | 4 |
| Cuscuta leptantha | Engelm. | Convolvulaceae | 4 |
| Cyperus hemidrummondii | Goetgh. | Cyperaceae | 4 |
| Cyperus setigerus | Torr. & Hook. | Cyperaceae | 4 |
| Dalea ceciliana | B.L.Turner | Fabaceae | 4 |
| Dichanthelium wrightianum | (Scribn.) Freckmann | Poaceae | 4 |
| Digitaria villosa | (Walter) Pers. | Poaceae | 4 |
| Eleocharis tortilis | (Link) Schult. | Cyperaceae | 4 |
| Elymus texensis | J.J.N.Campb. | Poaceae | 4 |
| Erigeron eximius | Greene | Asteraceae | 4 |
| Euphorbia spurca | (M.C.Johnst.) A.M.Powell | Euphorbiaceae | 4 |
| Fendlera linearis | Rehder | Hydrangeaceae | 4 |
| Fuirena pumila | (Torr.) Spreng. | Cyperaceae | 4 |
| Giliastrum ludens | (Shinners) J.M.Porter | Polemoniaceae | 4 |
| Helanthium tenellum | (Mart. ex Schult.f.) Britton | Alismataceae | 4 |
| Heliotropium glabriusculum | A.Gray | Heliotropiaceae | 4 |
| Heteranthera rotundifolia | (Kunth) Griseb. | Pontederiaceae | 4 |
| Hieracium schultzii | Fr. | Asteraceae | 4 |
| Hoffmannseggia drummondii | Torr. & A.Gray | Fabaceae | 4 |
| Houstonia parviflora | Holz. ex Greenm. | Rubiaceae | 4 |
| Ipomoea shumardiana | (Torr.) Shinners | Convolvulaceae | 4 |
| Isolepis pseudosetacea | (Daveau) Gand. | Cyperaceae | 4 |
| Lepidium ramosissimum | A.Nelson | Brassicaceae | 4 |
| Muenchhusia dasycalyx | (S.F.Blake & Shiller) M.M.Hanes & R.L.Barrett | Malvaceae | 4 |
| Muhlenbergia straminea | Hitchc. | Poaceae | 4 |
| Myriopteris aemula | (Maxon) Grusz & Windham | Pteridaceae | 4 |
| Nemastylis nuttallii | Pickering ex R.C.Foster | Iridaceae | 4 |
| Packera hartiana | (A.Heller) W.A.Weber & Á.Löve | Asteraceae | 4 |
| Packera millelobata | (Rydb.) W.A.Weber & Á.Löve | Asteraceae | 4 |
| Pycnanthemum clinopodioides | Torr. & A.Gray | Lamiaceae | 4 |
| Schoenoplectiella hallii | (A.Gray) Lye | Cyperaceae | 4 |
| Sidastrum paniculatum | (L.) Fryxell | Malvaceae | 4 |
| Solidago mollis | Bartl. | Asteraceae | 4 |
| Stemodia schottii | Holz. | Plantaginaceae | 4 |
| Streptanthus cutleri | Cory | Brassicaceae | 4 |
| Trichogalium correllii | (Dempster) Kadereit & Schneew. | Rubiaceae | 4 |
| Ulmus serotina | Sarg. | Ulmaceae | 4 |
| Verbena delticola | Small ex Perry | Verbenaceae | 4 |
| Vernonia marginata | (Torr.) Raf. | Asteraceae | 4 |
| Wissadula periplocifolia | (L.) Thwaites | Malvaceae | 4 |
| Xyris laxifolia | Mart. | Xyridaceae | 4 |
| Yeatesia platystegia | (Torr.) Hilsenb. | Acanthaceae | 4 |
| Agastache micrantha | (A.Gray) Wooton & Standl. | Lamiaceae | 3 |
| Allium elmendorfii | M.E.Jones ex Ownbey | Amaryllidaceae | 3 |
| Amaranthus crassipes | Schltdl. | Amaranthaceae | 3 |
| Ammannia grayi | S.A.Graham & Gandhi | Lythraceae | 3 |
| Amorpha laevigata | Nutt. | Fabaceae | 3 |
| Amsonia tharpii | Woodson | Apocynaceae | 3 |
| Andropogon tener | (Nees) Kunth | Poaceae | 3 |
| Asclepias elata | Benth. | Apocynaceae | 3 |
| Asclepias macrotis | Torr. | Apocynaceae | 3 |
| Asclepias scaposa | Vail | Apocynaceae | 3 |
| Astragalus waterfallii | Barneby | Fabaceae | 3 |
| Batesimalva violacea | (Rose) Fryxell | Malvaceae | 3 |
| Bouteloua erecta | (Vasey & Hack.) Columbus | Poaceae | 3 |
| Carex lupuliformis | Sartwell ex Dewey | Cyperaceae | 3 |
| Carex mesochorea | Mack. | Cyperaceae | 3 |
| Carex oklahomensis | Mack. | Cyperaceae | 3 |
| Ceratopteris thalictroides | (L.) Brongn. | Pteridaceae | 3 |
| Chaetopappa bellioides | (A.Gray) Shinners | Asteraceae | 3 |
| Chenopodium cycloides | A.Nelson | Chenopodiaceae | 3 |
| Chenopodium desiccatum | A.Nelson | Chenopodiaceae | 3 |
| Chloris texensis | Nash | Poaceae | 3 |
| Cochemiea wrightii | (Engelm. & J.M.Bigelow) Doweld | Cactaceae | 3 |
| Crataegus texana | Buckley | Rosaceae | 3 |
| Cuscuta legitima | Costea & Stefanović | Convolvulaceae | 3 |
| Cuscuta squamata | Engelm. | Convolvulaceae | 3 |
| Dalea laniceps | Barneby | Fabaceae | 3 |
| Dichanthelium transiens | (Swallen) Sánchez-Ken | Poaceae | 3 |
| Echinocereus canus | D.Felix & H.Bauer | Cactaceae | 3 |
| Echinocereus gurneyi | (L.D.Benson) W.Blum, Oldach & J.Oldach | Cactaceae | 3 |
| Echinocereus papillosus | Linke ex Rümpler | Cactaceae | 3 |
| Echinocereus reichenbachii | (Terscheck ex Walp.) J.N.Haage | Cactaceae | 3 |
| Echinochloa polystachya | (Kunth) Hitchc. | Poaceae | 3 |
| Erigeron versicolor | (Greenm.) G.L.Nesom | Asteraceae | 3 |
| Eriocoma robusta | (Vasey) Romasch. | Poaceae | 3 |
| Euphorbia perennans | (Shinners) Warnock & M.C.Johnst. | Euphorbiaceae | 3 |
| Eurytaenia texana | Torr. & A.Gray | Apiaceae | 3 |
| Galium uncinulatum | DC. | Rubiaceae | 3 |
| Helianthus neglectus | Heiser | Asteraceae | 3 |
| Heteranthera missouriensis | C.N.Horn | Pontederiaceae | 3 |
| Hypoxis sessilis | L. | Hypoxidaceae | 3 |
| Ipomoea rupicola | House | Convolvulaceae | 3 |
| Ipomoea tenuiloba | Torr. | Convolvulaceae | 3 |
| Leitneria pilosa | J.A.Schrad. & W.R.Graves | Simaroubaceae | 3 |
| Leucosyris parviflora | (A.Gray) Pruski & R.L.Hartm. | Asteraceae | 3 |
| Mandevilla brachysiphon | (Torr.) Pichon | Apocynaceae | 3 |
| Mimosa monclovensis | R.Grether & Marc.F.Simon | Fabaceae | 3 |
| Mitracarpus breviflorus | A.Gray | Rubiaceae | 3 |
| Muhlenbergia pauciflora | Buckley | Poaceae | 3 |
| Muhlenbergia repens | (J.Presl) Hitchc. | Poaceae | 3 |
| Nama undulata | Kunth | Namaceae | 3 |
| Oenothera arida | W.L.Wagner & Hoch | Onagraceae | 3 |
| Oenothera havardii | S.Watson | Onagraceae | 3 |
| Oenothera sessilis | (Pennell) Munz | Onagraceae | 3 |
| Orobanche multiflora | Nutt. | Orobanchaceae | 3 |
| Penstemon alamosensis | Pennell & Nisbet | Plantaginaceae | 3 |
| Penstemon cardinalis | Wooton & Standl. | Plantaginaceae | 3 |
| Penstemon wrightii | Hook. | Plantaginaceae | 3 |
| Phanerophlebia auriculata | Underw. | Dryopteridaceae | 3 |
| Physaria argyraea | (A.Gray) O'Kane & Al-Shehbaz | Brassicaceae | 3 |
| Potamogeton pulcher | Tuck. | Potamogetonaceae | 3 |
| Pseudoeriocoma eminens | (Cav.) Romasch. | Poaceae | 3 |
| Pteridium latiusculum | Hieron. | Dennstaedtiaceae | 3 |
| Pyrrocoma lanceolata | (Hook.) Greene | Asteraceae | 3 |
| Ranunculus cupulatus | (S.Watson) Christenh. & Byng | Ranunculaceae | 3 |
| Rhynchospora stenophylla | Chapm. | Cyperaceae | 3 |
| Scleria bellii | LeBlond | Cyperaceae | 3 |
| Setaria texana | Emery | Poaceae | 3 |
| Spiranthes eatonii | Ames ex P.M.Br. | Orchidaceae | 3 |
| Suckleya suckleyana | (Torr.) Rydb. | Chenopodiaceae | 3 |
| Thymophylla aurea | (A.Gray) Greene ex Britton & A.Br. | Asteraceae | 3 |
| Tiquilia mexicana | (S.Watson) A.T.Richardson | Ehretiaceae | 3 |
| Trichogalium microphyllum | (A.Gray) Kadereit & Schneew. | Rubiaceae | 3 |
| Valeriana texana | Steyerm. | Caprifoliaceae | 3 |
| Willkommia texana | Hitchc. | Poaceae | 3 |
| Xyris scabrifolia | R.M.Harper | Xyridaceae | 3 |
Abdra brachycarpa
Abronia ameliaeAmelia's Sand Verbena
Abronia angustifoliapurple sand verbena
Abronia carneawinged sandpuffs
Abronia fragranssnowball sand verbena
Abronia macrocarpalarge-fruited sand verbena
Abronia nealleyi
Abutilon abutiloidesshrubby Indian mallow
Abutilon fruticosumTexas Indian mallow
Abutilon hypoleucumwhiteleaf Indian mallow
Abutilon malacumyellow Indian mallow
Abutilon mollicomumSonoran Indian mallow
Abutilon parvulumdwarf Indian mallow
Abutilon trisulcatumanglestem Indian mallow
Abutilon viscosumviscid mallow
Abutilon wrightiiWright's Indian mallow
Acaciella angustissimaprairie acacia
Acalypha gracilensShortstalk Copperleaf
Acalypha monococcaslender threeseed mercury
Acalypha monostachyaround copperleaf
Acalypha neomexicanaNew Mexico copperleaf
Acalypha persimilispineland threeseed mercury
Acalypha phleoidesshrubby copperleaf
Acalypha poiretiiPoiret's copperleaf
Acalypha radianscardinal's feather
Acalypha rhomboideaCommon three-seeded copperleaf
Acalypha virginicaVirginia threeseed mercury
Acanthocereus tetragonusBarbed-wire cactus
Acer negundobox elder
Acer rubrumred maple
Acer saccharinumsilver maple
Acer saccharumsugar maple
Acleisanthes anisophyllaobliqueleaf trumpets
Acleisanthes chenopodioidesgoosefoot moonpod
Acleisanthes diffusaspreading moonpod
Acleisanthes lanceolatagypsum moonpod
Acleisanthes longifloraangel's trumpets
Acleisanthes obtusaBerlandier's trumpets
Acmella repens
Acmispon americanusSpanish clover
Acmispon brachycarpusfoothill deervetch
Acmispon oroboides
Acourtia nanadwarf desertpeony
Acourtia runcinatafeatherleaf desertpeony
Acourtia wrightiibrownfoot
Adelia vaseyiVasey's wild lime
Adiantum capillus-venerisblack maidenhair fern
Adiantum tricholepisfuzzy maidenhair
