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Vasey's Pondweed (Potamogeton vaseyi)

Life history

Species overview

Vasey's Pondweed (Potamogeton vaseyi), a Wisconsin Special Concern plant, is found in bays of large soft-water lakes as well as rivers and ponds. Blooming occurs throughout July; fruiting occurs early August through early September. The optimal identification period for this species is throughout August.

Synonyms: Potamogeton lateralis


  • Distinguishing characteristics: Floating leaves 1.5 to 12 cm; spikes 3 to 8 mm; submersed leaves thin and flat, 1- or 3-veined, up to 1 mm wide.
  • Flower characteristics: Spikes cyclindric, 3 to 8 mm, with 1 to 4 whorls of flowers.
  • Fruit characteristics: Obovoid, 1.5 to 2.5 mm, with flat or shallowly pitted sides, with or without a low, rounded dorsal keel.
  • Leaf characteristics: Submersed leaves thin and transparent, narrowly linear, 2 to 6 cm long by 0.2 to 1 mm wide, sharply acute; stipular sheaths free, linear, scarcely encircling the stem, 4 to 10 mm, weakly fibrous in age; floating leaves rather sparingly produced on at least some of the plants of a colony, the blade spatulate to obovate, 8 to 15 mm, 5- to 9-veined, the petiole approximately as long as the blade.


  • Blooming phenology: throughout July
  • Fruiting phenology: early August through early September
  • Optimum time to identify: The optimal identification period for this species is throughout August


  • Growth form: Aquatic forb-submergent/floating
  • Vegetative reproduction:
  • Life cycle: Annual
  • Comments: Associated Species: Elodea canadensis.

State status

Status and Natural Heritage Inventory documented occurrences in Wisconsin

The table below provides information about the protected status - state and federal - and the rank (S and G Ranks) for Vasey's Pondweed (Potamogeton vaseyi). See the Working List Key for more information about abbreviations. Counties shaded blue have documented occurrences for this species in the Wisconsin Natural Heritage Inventory database. The map is provided as a general reference of where this species has been found to date and is not meant as a range map.

Documented locations of Potamogeton vaseyi in the Natural Heritage Inventory Database as of July 2015.

Summary Information
State StatusSC
Federal Status in Wisconsinnone
State RankS3
Global RankG4
Tracked by NHIY

Habitats and landscapes

The Natural Heritage Inventory has developed scores indicating the degree to which each of Wisconsin's rare plant species is associated with a particular natural community or ecological landscape. This information is similar to that found in the Wildlife Action Plan for animals. As this is a work in progress, we welcome your suggestions and feedback.

General habitat information

  • Habitat description: Found in bays of large soft-water lakes as well as rivers and ponds.
  • Soils:

Natural communities

This table lists the natural communities that are associated with Vasey's Pondweed. Scores for natural community associations are: "significant" association (score=3), "moderate association" (score=2) or the species can be present but is only weakly associated with the community (score=1).

Ecological landscapes

This table lists the ecological landscape association scores for Vasey's Pondweed. The scores (3=High, 2=Moderate, 1=Low, 0=None) also correspond to the map.

Map of the Ecological Landscapes of Wisconsin.

Ecological landscape score
Forest Transition 2
North Central Forest 2
Northern Highland 2

Species guidance

The Endangered Resources Program has developed avoidance measures and management guidelines for plants on the Natural Heritage Working List. These are a work in progress, and we welcome your suggestions and feedback. Sources used in developing this information can be found here.

Avoidance measures

These are specific actions designed to avoid "take" (mortality) of this species.

  • Avoid known individual plant locations and conduct operations elsewhere when they are least likely to cause damage. Ideally, this would involve frozen, snow-covered ground. However, in areas of the state where frozen conditions are unreliable, very dry soils late in the growing season might be the best available alternative. Consult with a biologist, if needed.
  • Avoid broadcast spraying of herbicides; use care with spot spraying.

Management guidance

Management guidelines are additional considerations that may help maintain or enhance habitat for this species

  • This species is likely sensitive to water quality. Following BMPs around streams and buffering associated drainages will reduce eutrophication and prevent water quality degradation.


Vasey's Pondweed Photo.

The small floating leaves of Potamogeton vaseyi stand in contrast to the larger floating leaves of the more common P. natans in the center of this photo.

Photo © Matt Berg.

Vasey's Pondweed Photo.

Potamogeton vaseyi is fairly unique for having very narrow submerged leaves and small floating leaves.

Photo © Matt Berg.

Vasey's Pondweed Photo.

Photo ©  USDA-NRCS.

Support for Wisconsin's rare plant information has been provided by the Division of Forestry, the Endangered Resources Fund and the Wisconsin Rare Plant Preservation Fund. To donate, visit the Natural Resources Foundation of Wisconsin [exit DNR].

Last revised: Wednesday, May 05, 2021
Southwest Savanna Southern Lake Michigan Coastal Western Coulees and Ridges Southeast Glacial Plains Central Sand Hills Central Lake Michigan Coastal Central Sand Plains Northern Lake Michigan Coastal Northern Lake Michigan Coastal Northeast Sands Western Prairie North Central Forest Northern Highlands Northwest Lowlands Northwest Sands Northwest Lowlands Superior Coastal Plains Forest Transition