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Purple Threeawn (Aristida purpurea Nutt.)

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Range - Expand

Present: Various or Uncertain Origin
Native or Not Present
Introduced or Not Present
Native or Introduced
Native or Expanded or Not Present

This tentative map is based on our own research. It may have limited data on Canada and/or Mexico, and there is some subjectivity in our assignment of plants as introduced vs. expanded. Read more in this blog post.

This species is native and widespread in the west, including the western portions of the Great Plains, but it becomes uncommon and scattered in the eastern Great Plains. It is sometimes used in landscaping, and can escape into the wild; it is also favored by grazing as it is less attractive to livestock than other grasses. It has established in a number of eastern sites; we marked most of these populations Introduced because they are mostly isolated except for a few that were very close to the native range. Where exactly to make the cutoff represents a subjective judgment call, and we may update this map if we receive new information.


In North America, this species poses no known ecological risks and does not need to be eliminated for ecological reasons. East of its native range, it is usually not competitive with locally-native grasses.

Its presence on pastureland, especially east of its native range, is usually an indicator of poor grazing management. It can usually be eliminated by a change in management practices to reduce overgrazing, and/or the establishment of locally-native grasses better adapted to the more humid climate in the east.

Purple Threeawn | Fire Effects Information System (FEIS) (About This Site)

Aristida purpurea (purple threeawn) | USDA PLANTS Database (About This Site)

Aristida purpurea | Go Botany (About This Site)

Aristida purpurea | Biota of North America Project (BONAP) (About This Site)

Aristida purpurea Nutt. | Plants of the World Online (POWO) (About This Site)

Aristida purpurea | NatureServe Explorer (About This Site)

Aristida purpurea | Flora of North America (About This Site)