Polygonum minimumS.Watson

broadleaf knotweed

WFO wfo-0001101038 Accepted WFO 2026-06 8 photographs CC BY

Plate 1 figs. a–h · 8 separate observations

Polygonum minimum, photographed by Ken-ichi Ueda
fig. a Ken-ichi Ueda, CC BY 4.0 / 2015-07-29 / obs. 2271871
Polygonum minimum, photographed by Steve Matson
fig. b Steve Matson, CC BY 4.0 / obs. 117379400
Polygonum minimum, photographed by J Straka
fig. c J Straka, CC BY 4.0 / obs. 91382346
Polygonum minimum, photographed by Matt Berger
fig. d Matt Berger, CC BY 4.0 / obs. 53855196
Polygonum minimum, photographed by David Anderson
fig. e David Anderson, CC BY 4.0 / obs. 50169945
Polygonum minimum, photographed by Matt Berger
fig. f Matt Berger, CC BY 4.0 / obs. 47177992
Polygonum minimum, photographed by Matt Berger
fig. g Matt Berger, CC BY 4.0 / obs. 52356220
Polygonum minimum, photographed by Alison Northup
fig. h Alison Northup, CC BY 4.0 / obs. 50143111

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 12 botanical countries

Regions where Polygonum minimum is native: Alaska, Alberta, British Columbia, California, Colorado, Idaho, Montana, Nevada, Oregon, Utah, Washington, Wyoming AlaskaAlbertaBritish ColumbiaCaliforniaColoradoIdahoMontanaNevadaOregonUtahWashingtonWyoming
Native distribution of Polygonum minimum, 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.
RegionTDWG codeContinent
Alaska ASK NORTHERN AMERICA
Alberta ABT
British Columbia BRC
California CAL
Colorado COL
Idaho IDA
Montana MNT
Nevada NEV
Oregon ORE
Utah UTA
Washington WAS
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 1 synonym

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.

  • Polygonum torreyi S.Watson

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.