Asclepias purpurascens
Purple milkweed
Image of Asclepias purpurascens

Photo by Bradford S. Slaughter 

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Key Characteristics

Perennial forb of woodlands, savannas, prairies, and wetlands; leaves opposite on short petioles with dense short hairs below, tips acute; flowers purple, borne in 1-3 terminal clusters.

Status and Rank

  • State Status: T
  • State Rank: S2
  • Global Rank: G5?


County NameNumber of OccurrencesYear Last Observed
St. Clair32006
St. Joseph32010
Van Buren52008
Distribution map for Asclepias purpurascens

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.


Found in a variety of habitat types, including oak and oak-pine woodlands, savanna, dry to wet prairies, thickets, prairie fens and shrub-carr.

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

Bluejoint grass, cordgrass, rush, sedges, twig-rush, shrubby cinquefoil, swamp milkweed, big bluestem, Indian grass, Sullivant's milkweed, purple milkweed, swamp thistle, eastern prairie fringed orchid, marsh blazing star, whorled loosestrife, grass-of-Parnassus, smooth hedge nettle, swamp rose, Missouri ironweed, prairie dropseed, three-awn grass, ironweed, tall coreopsis, and creeping cinquefoil. In oak barrens, it may also be associated with black oak, white oak, bur oak, bitternut hickory, pignut hickory, shagbark hickory, leadplant, butterfly weed, little bluestem, and big bluestem.


Maintain hydrological and natural disturbance regimes. This species most likely requires open conditions. Prevent woody plant encroachment by using prescribed fire or manual brush removal. Much of this habitat has been lost and degraded via conversion to agriculture, development, alterations of hydrology via drains, and fire suppression.

General Survey Guidelines

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

Survey Methods

Page Citation

Michigan Natural Features Inventory. 2007. Rare Species Explorer (Web Application). Available online at [Accessed Aug 16, 2018]

More Information

See MNFI Species Abstract


Survey References

Technical References

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