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Slender Pondweed (Stuckenia filiformis ssp. occidentalis)

Life history

Species overview

Slender Pondweed (Stuckenia filiformis ssp. occidentalis), a Wisconsin Special Concern plant, is found in cold streams and rivers, more rarely in standing waters. Blooming occurs from spring to early fall. The optimal identification period for this species is spring to early fall.

Synonyms: Coleogeton filiformis, Potamogeton filiformis ssp. occidentalis, Potamogeton interior, Stuckenia filiformis var. occidentalis


  • Distinguishing characteristics: This subspecies of Stuckenia filiformis rarely produces mature fruit. Of other Stuckenia species found in Wisconsin, Stuckenia vaginata has midstem stipular sheaths that are disticntly inflated; Stuckenia pectinata has acute leaf apexes; and Stuckenia filiformis ssp. Alpina has tightly clasping stipules.
  • Flower characteristics: 4-parted flowers in a spike, with flowers and/or fruits 2 cm or less apart from each other.
  • Fruit characteristics: Produces drupes, but mature fruits are rare.
  • Leaf characteristics: Alternate leaves have a prominent midvein and are very narrow, 0.2 to 5 mm wide with blunt, notched apexes. Stipular sheaths on the lower stems are loosely clasping and often inflated, but disintegrate with age.


  • Blooming phenology: spring to early fall
  • Fruiting phenology:
  • Optimum time to identify: The optimal identification period for this species is spring to early fall


  • Growth form: Aquatic herb
  • Vegetative reproduction: Rhizomatous
  • Life cycle: Perennial
  • Comments:

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 Slender Pondweed (Stuckenia filiformis ssp. occidentalis). 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 Stuckenia filiformis ssp. occidentalis in the Natural Heritage Inventory Database as of July 2015.

Summary Information
State StatusSC
Federal Status in Wisconsinnone
State RankS2
Global RankG5T5
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 cold streams and rivers, more rarely in standing waters.
  • Soils:

Natural communities

This table lists the natural communities that are associated with Slender 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).

Natural communities score
Coolwater streams 3
Warmwater rivers 3
Submergent Marsh 3

Ecological landscapes

This table lists the ecological landscape association scores for Slender 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 3
Northwest Sands 3
Superior Coastal Plain 3

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.

  • No avoidance measures have been developed for this species.

Management guidance

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

  • No guidance has been developed for this species.


Slender Pondweed Photo.

Scanned specimen courtesy of Wisconsin Herbarium

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