Stylosanthes biflora(L.) Britton, Sterns & Poggenb.

sidebeak pencilflower

WFO wfo-0000164070 Accepted WFO 2026-06 8 photographs CC0 / CC BY

Plate 1 figs. a–h · 8 separate observations

Stylosanthes biflora, photographed by drnancyjackson
fig. a drnancyjackson, CC BY 4.0 / 2022-06-04 / obs. 203289328

Every figure is a research-grade observation under CC0, CC BY or CC BY-SA, rehosted with the photographer’s name, the licence and the observation it came from. Photographs under a NonCommercial licence are excluded from this site and are never stored, which costs us a great many pictures and is not negotiable.

Native range 22 botanical countries

Regions where Stylosanthes biflora is native: Alabama, Arkansas, Delaware, District of Columbia, Florida, Georgia, Illinois, Iowa, Kentucky, Louisiana, Maryland, Mississippi, Missouri, New Jersey, New York, North Carolina, Oklahoma, South Carolina, Tennessee, Texas, Virginia, West Virginia AlabamaArkansasFloridaGeorgiaIllinoisIowaKentuckyLouisianaMarylandMississippiMissouriNew JerseyNew YorkNorth CarolinaOklahomaSouth CarolinaTennesseeTexasVirginiaWest Virginia DelawareDistrict of Columbia
Native distribution of Stylosanthes biflora, after Kew’s World Checklist of Vascular Plants. Introduced, extinct and doubtful records are excluded, so this is where the plant is from, not everywhere it now grows. Regions too small to draw at this scale are marked with a dot.
RegionTDWG codeContinent
Alabama ALA NORTHERN AMERICA
Arkansas ARK
Delaware DEL
District of Columbia WDC
Florida FLA
Georgia GEO
Illinois ILL
Iowa IOW
Kentucky KTY
Louisiana LOU
Maryland MRY
Mississippi MSI
Missouri MSO
New Jersey NWJ
New York NWY
North Carolina NCA
Oklahoma OKL
South Carolina SCA
Tennessee TEN
Texas TEX
Virginia VRG
West Virginia WVA

Region boundaries approximated from Natural Earth (public domain) and mapped to TDWG World Geographical Scheme for Recording Plant Distributions (WGSRPD) level-3 botanical countries (Brummitt 2001). Indicative, not the official WGSRPD geometry.

Flowering 580 in flower of 612 examined

Proportion of examined Stylosanthes biflora in flower, by month
Month In flower Examined Share 95% interval
Jan 0 0 too few examined
Feb 0 0 too few examined
Mar 1 1 too few examined
Apr 23 23 100% 86% to 100%
May 132 142 93% 88% to 96%
Jun 156 164 95% 91% to 98%
Jul 137 143 96% 91% to 98%
Aug 81 85 95% 89% to 98%
Sep 39 42 93% 81% to 98%
Oct 10 11 91% 62% to 98%
Nov 0 0 too few examined
Dec 1 1 too few examined

Peak flowering in Apr. Each bar is the share of Stylosanthes biflora observations in which someone actually recorded the reproductive state and found the plant in flower, not the raw number of flowering records. That distinction matters: people observe plants far more in spring than in winter, so a bare count of flowering records partly measures when people go outside. Dividing by the number examined removes that. 580 of 612 examined observations were in flower, every one of them research grade. The whisker on each bar is a 95% Wilson interval. 5 months have fewer than 5 examined observations, so no proportion is drawn for them. This is still a global aggregate and not a forecast for your garden: the same species flowers on different dates in different hemispheres. Where a species has fewer than 30 flowering records we do not draw this chart at all. Computed from 10.15468/dl.cgje2x.

Where it actually grows measured, from 1,948 observations

Condition 5th percentile Median 95th percentile
Coldest month, mean daily low -3.2 °C 1.2 °C 8.1 °C
Warmest month, mean daily high 29.5 °C 31.6 °C 34.1 °C
Annual rainfall 1,037 mm 1,274 mm 1,642 mm
Rainfall in the driest quarter 177 mm 258 mm 338 mm

It is found where winters bring light frost. This is not care advice and it is not a forecast. It is a measurement: we sampled the climate at every one of the 1,948 research-grade observations of Stylosanthes biflora that carry a coordinate, and this is the range those places actually span. The 5th and 95th percentiles are used rather than the minimum and maximum, because a single cultivated specimen in a heated conservatory should not widen a tropical plant's range to the Arctic.

This is not a hardiness zone. A USDA zone is the average annual extreme minimum temperature. The figure above is the mean daily minimum of the coldest month, which is a different quantity and is typically far warmer. Reading one as the other would place a plant several zones too warm, so we do not publish a hardiness zone, because we do not have one. Climate from CHELSA V2.1 (Karger et al. 2017); occurrences from 10.15468/dl.cgje2x.

Also published as 17 synonyms

A synonym is not an error. It is a record of botanists disagreeing, in print, about where this plant belongs. Each of these was somebody’s considered answer.

  • Arachis aprica Walter
  • Stylosanthes biflora var. elatior (Sw.) Kuntze
  • Stylosanthes biflora var. hispidissima (Michx.) Pollard & C.R.Ball
  • Stylosanthes biflora var. hispidissima (Michx.) Pollard & C.R.Ball
  • Stylosanthes elatior Sw.
  • Stylosanthes elatior var. hispidissima (Michx.) Torr. & A.Gray
  • Stylosanthes floridana S.F.Blake
  • Stylosanthes hispida Michx.
  • Stylosanthes hispida var. erecta Pursh
  • Stylosanthes hispida var. hispidissima Michx.
  • Stylosanthes hispida var. nudiuscula Michx.
  • Stylosanthes hispida var. procumbens Pursh
  • Stylosanthes hispidissima (Michx.) Anon.
  • Stylosanthes riparia Kearney
  • Stylosanthes riparia var. setifera Fernald
  • Trifolium biflorum L.
  • Trifolium hispidissimum Michx. ex Steud.

Sourcesevery claim on this page

  1. World Flora Online Plant List. accepted name, authority, classification. CC0. Retrieved 2026-07-12.
  2. iNaturalist. photographs and flowering annotations, CC0 / CC BY / CC BY-SA only. per photograph. Retrieved 2026-06-27.
  3. Wikidata. common name (P1843), joined on the World Flora Online identifier (P7715). CC0. Retrieved 2026-07-13.
  4. Kew, World Checklist of Vascular Plants (WCVP v16). native distribution by TDWG level-3 botanical country, and life form. CC BY 3.0. Retrieved 2026-06-04.

We publish what we can source and we say so when we cannot. This page has no care advice and no toxicity claim, because we do not yet have those from a source we can cite.