Hydrocotyle americanaL.

American marshpennywort

WFO wfo-0000726327 Accepted WFO 2026-06 8 photographs CC0 / CC BY

Plate 1 figs. a–h · 8 separate observations

Hydrocotyle americana, photographed by Steven Lamonde
fig. a Steven Lamonde, CC BY 4.0 / 2022-06-02 / obs. 205769601
Hydrocotyle americana, photographed by Bruce Cook
fig. b Bruce Cook, CC0 1.0 / obs. 201386539
Hydrocotyle americana, photographed by Lynn Harper
fig. c Lynn Harper, CC0 1.0 / obs. 201083678
Hydrocotyle americana, photographed by Bonnie Semmling
fig. d Bonnie Semmling, CC BY 4.0 / obs. 196670807
Hydrocotyle americana, photographed by Steven Lamonde
fig. e Steven Lamonde, CC BY 4.0 / obs. 164909136
Hydrocotyle americana, photographed by Lynn Harper
fig. f Lynn Harper, CC0 1.0 / obs. 164065408
Hydrocotyle americana, photographed by Lynn Harper
fig. g Lynn Harper, CC0 1.0 / obs. 163171907
Hydrocotyle americana, photographed by Lynn Harper
fig. h Lynn Harper, CC0 1.0 / obs. 160704421

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 30 botanical countries

Regions where Hydrocotyle americana is native: Arkansas, Connecticut, Delaware, District of Columbia, Indiana, Kentucky, Maine, Maryland, Massachusetts, Michigan, Minnesota, New Brunswick, New Hampshire, New Jersey, New York, Newfoundland, North Carolina, Nova Scotia, Ohio, Ontario, Pennsylvania, Prince Edward I., Québec, Rhode I., South Carolina, Tennessee, Vermont, Virginia, West Virginia, Wisconsin ArkansasConnecticutIndianaKentuckyMaineMarylandMassachusettsMichiganMinnesotaNew BrunswickNew HampshireNew JerseyNew YorkNewfoundlandNorth CarolinaNova ScotiaOhioOntarioPennsylvaniaPrince Edward I.QuébecSouth CarolinaTennesseeVermontVirginiaWest VirginiaWisconsin DelawareDistrict of ColumbiaRhode I.
Native distribution of Hydrocotyle americana, 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
Arkansas ARK NORTHERN AMERICA
Connecticut CNT
Delaware DEL
District of Columbia WDC
Indiana INI
Kentucky KTY
Maine MAI
Maryland MRY
Massachusetts MAS
Michigan MIC
Minnesota MIN
New Brunswick NBR
New Hampshire NWH
New Jersey NWJ
New York NWY
Newfoundland NFL
North Carolina NCA
Nova Scotia NSC
Ohio OHI
Ontario ONT
Pennsylvania PEN
Prince Edward I. PEI
Québec QUE
Rhode I. RHO
South Carolina SCA
Tennessee TEN
Vermont VER
Virginia VRG
West Virginia WVA
Wisconsin WIS

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 292 in flower of 634 examined

Peak flowering in Jul. Each bar is the share of Hydrocotyle americana 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. 292 of 634 examined observations were in flower, every one of them research grade. The whisker on each bar is a 95% Wilson interval. 6 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.

Also published as 3 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.

  • Hydrocotyle americana var. flexicaulis Michx.
  • Hydrocotyle americana var. gracilis Michx.
  • Hydrocotyle nitens Colenso

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.