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Purple False Oats (Trisetum melicoides)

Life history

Species overview

Purple False Oats (Trisetum melicoides), a Wisconsin Endangered plant, is found in mixed forests near Lake Michigan, as well as in ridge and swale systems and on shoreline dolomite and seeping bluffs. Blooming occurs from June. The optimal identification period for this species is mid-July to late August.

Synonyms: Aira melicoides; Graphephorum melicoideum; G. melicoides var majus; T. melicoides var. majus


  • Distinguishing characteristics: Can be distinguished from the only other Trisetum species in Wisconsin by height (greater than 30 cm) and the absence of awns on spikelets.
  • Flower characteristics: Panicle somewhat open, nodding, 10 to 20 cm long; branches slender, ascending, lax or drooping, as much as 7 cm long, rather closely flowered above the middle; spikelets scaberulous, 6 to 7 mm long.
  • Fruit characteristics: Glumes 4 to 6 mm long, the second longer and broader; lemmas acute, 5 to 6 mm long, rarely with a minute awn just below the tip; the rachilla and callus hairs 1 to 2 mm long.
  • Leaf characteristics: Leaf blades 2 to 8 mm wide, scabrous, sometimes pubescent on the upper surface; Sheaths pubescent or scabrous.


  • Blooming phenology: June
  • Fruiting phenology:
  • Optimum time to identify: The optimal identification period for this species is mid-July to late August


  • Growth form: Graminoid
  • Vegetative reproduction:
  • Life cycle: Perennial
  • Comments: Associated Species: Acer saccharum, Fagus grandifolia, Tilia americana, Thuja occidentalis, Abies balsamea, Carex eburnea, C. concinna, Trientalis borealis, Cornus canadensis, Parnassia glauca, Halenia deflexa, Polygala paucifolia.

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 Purple False Oats (Trisetum melicoides). 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 Trisetum melicoides in the Natural Heritage Inventory Database as of July 2015.

Summary Information
State StatusEND
Federal Status in Wisconsinnone
State RankS1
Global RankG4G5
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 mixed forests near Lake Michigan, as well as in ridge and swale systems and on shoreline dolomite and seeping bluffs.
  • Soils: Gravelly or rocky soils

Natural communities

This table lists the natural communities that are associated with Purple False Oats. 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 Purple False Oats. The scores (3=High, 2=Moderate, 1=Low, 0=None) also correspond to the map.

Map of the Ecological Landscapes of Wisconsin.

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 disturbance to streambanks and calcareous rock ledges within forests where this species has been reported
  • Avoid broadcast spraying of herbicides; use care with spot spraying.
  • 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.

Management guidance

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

  • Buffer management around unique microhabitats such as ephemeral ponds, seeps, etc.
  • Minimize disturbance to hydrology, including soil disturbance from rutting.
  • Follow BMPs, especially around streams and use care near ravines, steep slopes, cliffs, rock outcrops, etc.


Purple False Oats Photo.

Photo © Emmet Judziewicz.

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