Polygonum ramosissimumMichx.

bushy knotweed

WFO wfo-0000489215 Accepted WFO 2026-06 6 photographs CC0 / CC BY

Plate 1 figs. a–f · 3 observations

This species has been photographed under an open licence only 3 times, so some figures below are different views of the same plant, taken on the same day, rather than different individuals. They are usually different parts of it: the leaf, the flower, the bark.

Polygonum ramosissimum, photographed by Sam Kieschnick
fig. a Sam Kieschnick, CC BY 4.0 / 2017-08-12 / obs. 9738308
Polygonum ramosissimum, photographed by Sam Kieschnick
fig. b Sam Kieschnick, CC BY 4.0 / obs. 9738309
Polygonum ramosissimum, photographed by Sam Kieschnick
fig. c Sam Kieschnick, CC BY 4.0 / obs. 9738310
Polygonum ramosissimum, photographed by Sam Kieschnick
fig. d Sam Kieschnick, CC BY 4.0 / obs. 9738311
Polygonum ramosissimum, photographed by Daniel Atha
fig. e Daniel Atha, CC0 1.0 / obs. 5373414
Polygonum ramosissimum, photographed by Daniel Atha
fig. f Daniel Atha, CC0 1.0 / obs. 5905577

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 58 botanical countries

Regions where Polygonum ramosissimum is native: Alabama, Alberta, Arizona, Arkansas, British Columbia, California, Colorado, Connecticut, Delaware, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Manitoba, Maryland, Massachusetts, Mexico Northwest, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Brunswick, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Northwest Territories, Nova Scotia, Ohio, Oklahoma, Ontario, Oregon, Pennsylvania, Prince Edward I., Québec, Rhode I., Saskatchewan, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, Wyoming AlabamaAlbertaArizonaArkansasBritish ColumbiaCaliforniaColoradoConnecticutGeorgiaIdahoIllinoisIndianaIowaKansasKentuckyLouisianaMaineManitobaMarylandMassachusettsMexico NorthwestMichiganMinnesotaMississippiMissouriMontanaNebraskaNevadaNew BrunswickNew HampshireNew JerseyNew MexicoNew YorkNorth CarolinaNorth DakotaNorthwest TerritoriesNova ScotiaOhioOklahomaOntarioOregonPennsylvaniaPrince Edward I.QuébecSaskatchewanSouth CarolinaSouth DakotaTennesseeTexasUtahVermontVirginiaWashingtonWest VirginiaWisconsinWyoming DelawareRhode I.
Native distribution of Polygonum ramosissimum, 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
Alberta ABT
Arizona ARI
Arkansas ARK
British Columbia BRC
California CAL
Colorado COL
Connecticut CNT
Delaware DEL
Georgia GEO
Idaho IDA
Illinois ILL
Indiana INI
Iowa IOW
Kansas KAN
Kentucky KTY
Louisiana LOU
Maine MAI
Manitoba MAN
Maryland MRY
Massachusetts MAS
Mexico Northwest MXN
Michigan MIC
Minnesota MIN
Mississippi MSI
Missouri MSO
Montana MNT
Nebraska NEB
Nevada NEV
New Brunswick NBR
New Hampshire NWH
New Jersey NWJ
New Mexico NWM
New York NWY
North Carolina NCA
North Dakota NDA
Northwest Territories NWT
Nova Scotia NSC
Ohio OHI
Oklahoma OKL
Ontario ONT
Oregon ORE
Pennsylvania PEN
Prince Edward I. PEI
Québec QUE
Rhode I. RHO
Saskatchewan SAS
South Carolina SCA
South Dakota SDA
Tennessee TEN
Texas TEX
Utah UTA
Vermont VER
Virginia VRG
Washington WAS
West Virginia WVA
Wisconsin WIS
Wyoming WYO

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.

Also published as 15 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.

  • Cnopos ramosissimum (Michx.) Raf.
  • Polygonum atlanticum (B.L.Rob.) E.P.Bicknell
  • Polygonum autumnale Brenckle
  • Polygonum exsertum Small
  • Polygonum interior Brenckle
  • Polygonum latum Small ex Rydb.
  • Polygonum leptocarpum B.L.Rob.
  • Polygonum prolificum (Small) B.L.Rob.
  • Polygonum prolificum var. autumnale (Brenckle) Brenckle
  • Polygonum prolificum var. profusum Brenckle
  • Polygonum ramosissimum f. ramosissimum
  • Polygonum ramosissimum subsp. ramosissimum
  • Polygonum ramosissimum var. prolificum Small
  • Polygonum stevensii Brenckle
  • Polygonum triangulum E.P.Bicknell ex Small

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.