Potamogeton bicupulatusFernald

snailseed pondweed

WFO wfo-0000719354 Accepted WFO 2026-06 4 photographs CC BY

Plate 1 figs. a–d · 1 observation

This species has been photographed under an open licence only 1 time, 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.

Potamogeton bicupulatus, photographed by Quinten Wiegersma
fig. a Quinten Wiegersma, CC BY 4.0 / 2021-09-14 / obs. 157460927
Potamogeton bicupulatus, photographed by Quinten Wiegersma
fig. b Quinten Wiegersma, CC BY 4.0 / obs. 157460958
Potamogeton bicupulatus, photographed by Quinten Wiegersma
fig. c Quinten Wiegersma, CC BY 4.0 / obs. 157461010
Potamogeton bicupulatus, photographed by Quinten Wiegersma
fig. d Quinten Wiegersma, CC BY 4.0 / obs. 157461035

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.

The specimen a real sheet, in a real collection

Herbarium
The New York Botanical Garden
Accession
3708714
Filed as
Potamogeton bicupulatus Fernald
Det. by
not recorded on this sheet
Collected
not recorded
Origin
not recorded
The sheet
View the digitised specimen (CC BY 4.0)

A real pressed plant, in a real collection, under the accession number above. Not an illustration of one. The holding institution does not serve this sheet’s image to third parties, so there is no photograph here. The record is real and the link goes to it. Where we hold no openly licensed sheet for a species this section is simply absent, and where a sheet never recorded who determined it, that field stays empty rather than being filled in. Roughly half of all herbarium sheets never recorded a determiner, which is ordinary.

Native range 19 botanical countries

Regions where Potamogeton bicupulatus is native: Connecticut, Delaware, Illinois, Indiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, New Hampshire, New York, Ontario, Pennsylvania, Rhode I., Tennessee, Vermont, Virginia, West Virginia, Wisconsin ConnecticutIllinoisIndianaMaineMarylandMassachusettsMichiganMinnesotaNew HampshireNew YorkOntarioPennsylvaniaTennesseeVermontVirginiaWest VirginiaWisconsin DelawareRhode I.
Native distribution of Potamogeton bicupulatus, 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
Connecticut CNT NORTHERN AMERICA
Delaware DEL
Illinois ILL
Indiana INI
Maine MAI
Maryland MRY
Massachusetts MAS
Michigan MIC
Minnesota MIN
New Hampshire NWH
New York NWY
Ontario ONT
Pennsylvania PEN
Rhode I. RHO
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.

Where it actually grows measured, from 49 observations

Condition 5th percentile Median 95th percentile
Coldest month, mean daily low -15.0 °C -9.9 °C -1.6 °C
Warmest month, mean daily high 22.5 °C 24.8 °C 27.6 °C
Annual rainfall 819 mm 1,120 mm 1,481 mm
Rainfall in the driest quarter 87 mm 228 mm 327 mm

It is found where winters bring hard 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 49 research-grade observations of Potamogeton bicupulatus 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.

Also published as 4 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.

  • Potamogeton dimorphus Raf.
  • Potamogeton diversifolius W.P.C.Barton
  • Potamogeton diversifolius var. trichophyllus Morong
  • Potamogeton hybridus var. trichophyllus (Morong) Graebn.

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.