Persicaria amphibia(L.) Delarbre

water smartweed

WFO wfo-0000488056 Accepted WFO 2026-06 8 photographs CC0 / CC BY

Plate 1 figs. a–h

Persicaria amphibia, photographed by Aiva Noringseth
fig. a Aiva Noringseth, CC BY 4.0 / 2022-06-11 / obs. 205249492
Persicaria amphibia, photographed by Marina Potapova
fig. b Marina Potapova, CC0 1.0 / obs. 203207786
Persicaria amphibia, photographed by Michel Langeveld
fig. c Michel Langeveld, CC BY 4.0 / obs. 205162776
Persicaria amphibia, photographed by Владимир Преловский
fig. d Владимир Преловский, CC0 1.0 / obs. 204309917
Persicaria amphibia, photographed by Michel Langeveld
fig. e Michel Langeveld, CC BY 4.0 / obs. 199397505
Persicaria amphibia, photographed by Michel Langeveld
fig. f Michel Langeveld, CC BY 4.0 / obs. 194745151
Persicaria amphibia, photographed by R Clarke
fig. g R Clarke, CC BY 4.0 / obs. 195136393
Persicaria amphibia, photographed by Michel Langeveld
fig. h Michel Langeveld, CC BY 4.0 / obs. 193138670

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.

Confused withby our own model

These are not lookalikes we guessed at. Each one is a species our identification model genuinely mistook for this plant, and how many times. The error rate is published.

Flowering n = 2,271 observations

Peak flowering in Aug, from 2,271 community-annotated observations worldwide. This is a global aggregate, not a forecast for your garden: the same species flowers on different dates in different hemispheres, and citizen-science records cluster near cities, at weekends, and in spring. Where a species has fewer than 30 annotated records we do not draw this chart at all.

Also published as 29 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.

  • Chulusium amphibium (L.) Raf.
  • Chulusium fluitans Raf.
  • Chulusium natans Raf.
  • Persicaria amphibia (L.) Gray
  • Persicaria amphibia var. emersa (Michx.) J.C.Hickman
  • Persicaria amphibia var. stipulacea (N.Coleman) H.Hara
  • Persicaria amphibia var. terrestris (Leyss.) Munshi & Javeid
  • Persicaria amurensis Nieuwl.
  • Persicaria coccinea (Muhl. ex Willd.) Greene
  • Persicaria hartwrightii (A.Gray) Greene
  • Persicaria muhlenbergii (S.Watson) Small
  • Polygonum amphibium L.
  • Polygonum amphibium subsp. laevimarginatum Hultén
  • Polygonum amphibium var. amurense Korsh.
  • Polygonum amphibium var. emersum Michx.
  • Polygonum amphibium var. muehlenbergii Meisn.
  • Polygonum amphibium var. natans Leyss.
  • Polygonum amphibium var. stipulaceum N.Coleman
  • Polygonum amphibium var. terrestre Leyss.
  • Polygonum amphibium var. vestitum Hemsl.
  • Polygonum coccineum Muhl. ex Willd.
  • Polygonum coccineum var. pratincola (Greene) Stanford
  • Polygonum coccineum var. rigidulum Stanford
  • Polygonum emersum (Michx.) Britton

and 5 more.

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.

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