Potamogeton bicupulatus
Waterthread pondweed
Image of Potamogeton bicupulatus

Photo by Robert W. Freckmann 

More Images

Key Characteristics

Aquatic plant of shallow softwater lakes; leaves submerged, very slender and thread-like (0.5 mm), alternate; floating leaves leathery, opposite, narrow (<1 cm), with 3-7 impressed veins.

Status and Rank

  • State Status: T
  • State Rank: S2
  • Global Rank: G4


County NameNumber of OccurrencesYear Last Observed
Van Buren11986
Distribution map for Potamogeton bicupulatus

Updated 5/15/2018. Information is summarized from MNFI's database of rare species and community occurrences. Data may not reflect true distribution since much of the state has not been thoroughly surveyed.


Waterthread pondweed is found in seasonally flooded wetlands formed in shallow depressions and potholes in glacial lakeplain and outwash landscapes.

Natural Community Types


For each species, lists of natural communities were derived from review of the nearly 6,500 element occurrences in the MNFI database, in addition to herbarium label data for some taxa. In most cases, at least one specimen record exists for each listed natural community. For certain taxa, especially poorly collected or extirpated species of prairie and savanna habitats, natural community lists were derived from inferences from collection sites and habitat preferences in immediately adjacent states (particularly Indiana and Illinois). Natural communities are not listed for those species documented only from altered or ruderal habitats in Michigan, especially for taxa that occur in a variety of habitats outside of the state.

Natural communities are not listed in order of frequency of occurrence, but are rather derived from the full set of natural communities, organized by Ecological Group. In many cases, the general habitat descriptions should provide greater clarity and direction to the surveyor. In future versions of the Rare Species Explorer, we hope to incorporate natural community fidelity ranks for each taxon.

Associated Plants

Robbin's spike-rush, pickerel weed, spatterdock, pipewort, water smartweed, floating bladderwort, Small's spike-rush, bluejoint grass, mermaid weed, and brown-fruited rush.


This species requires protection of habitat and maintenance of hydrology. It is susceptible to excessive recreational use and ORV traffic during low water periods.

General Survey Guidelines

Random meander search covers areas that appear likely to have rare taxa, based on habitat and the judgement of the investigator.

Survey Methods

Page Citation

Michigan Natural Features Inventory. 2007. Rare Species Explorer (Web Application). Available online at http://mnfi.anr.msu.edu/explorer [Accessed Sep 24, 2018]


Survey References

Technical References

Facebook link