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Minute Duckweed (Lemna perpusilla)

Life history

Species overview

Minute Duckweed (Lemna perpusilla), a plant, is found in quiet waters. Blooming occurs from late spring through fall. The optimal identification period for this species is late spring through fall.



  • Distinguishing characteristics: Root tips are usually sharp pointed. Most likely to be confused with Lemna aequinoctialis, which has a single papule on the dorsal side of the leaf whereas Lemna perpusilla has a few.
  • Flower characteristics: Tiny flowers with no perianth. Inflorescence consists of two male flowers and 1 female flower, enclosed in a spathe like a sac.
  • Fruit characteristics: Utricle that opens on one side, 0.7 to 1 mm long and without wings. Seeds have 35 to 70 ribs.
  • Leaf characteristics: Fronds are more or less convex on both sides, 1 to a few and ovate to obovate, flat, 1 to 4 mm long and 1 to 1.7 times longer than wide. 1 distinct papule at the node and a few distinct papules above the node. No anthocyanin is present in this species.


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


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

State status

Status and Natural Heritage Inventory documented occurrences in Wisconsin

Minute Duckweed (Lemna perpusilla) is on the "watch list." Watch list species have experienced, or are believed to have experienced, a statewide or range wide decline, but they are not currently tracked in the Natural Heritage Inventory (NHI) database. The watch list includes newly discovered species for which origin and rarity need to be determined, certain animals designated as Species of Greatest Conservation Need (SGCN) in the Wisconsin Wildlife Action Plan, and species that were tracked in the past but proved more abundant, widespread or less vulnerable than previously thought. Although watch list species are not actively tracked by NHI, occurrences documented during surveys are often stored by NHI, as these species could be tracked in the future if there is further evidence of their decline.

Summary Information
State Statusnone
Federal Status in Wisconsinnone
State RankSU
Global RankG5
Tracked by NHIW

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 quiet waters.
  • Soils:

Natural communities

This table lists the natural communities that are associated with Minute Duckweed. 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

Ecological landscapes

This table lists the ecological landscape association scores for Minute Duckweed. 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

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.


Minute Duckweed Photo.

Photo by  staff, Wisconsin DNR.

Minute Duckweed 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