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Purple Milkweed (Asclepias purpurascens)

Life history

Species overview

Purple Milkweed (Asclepias purpurascens), a Wisconsin Endangered plant, is found in open oak forests, forest margins, and roadsides. Blooming occurs early June through late July; fruiting occurs early July through late August. The optimal identification period for this species is late June through late July.

Synonyms: None


  • Distinguishing characteristics: Distinguished by its bright pink to purple, mostly terminal flowers containing reflexed, glabrous corolla lobes (vs. pubescent in A. syriaca). The leaves are hairy below and usually more acute than the rounded leaves of A. syriaca and less pinnately veined.
  • Flower characteristics: One terminal flower head with one or two additional flower heads in the upper part of plant; flowers bright pink to purple, reflexed, with glabrous corolla lobes, pale purple hoods 5 to 7 mm long, and incurved flat horns that are shorter than the hood.
  • Fruit characteristics: Downy pod.
  • Leaf characteristics: Opposite, elliptic to ovate leaves 10 to 15 cm in length with acute tips, hairy on underside with 8 to 25 mm petioles.


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


  • Growth form: Forb-erect
  • Vegetative reproduction: Rhizomatous
  • Life cycle: Perennial
  • Comments: Associated Species: Quercus alba, Q. velutina, Q. macrocarpa. It has wide soil moisture tolerances

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 Milkweed (Asclepias purpurascens). 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 Asclepias purpurascens in the Natural Heritage Inventory Database as of July 2015.

Summary Information
State StatusEND
Federal Status in Wisconsinnone
State RankS3
Global RankG5?
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 open oak forests, forest margins, and roadsides.
  • Soils: Sandy soils.

Natural communities

This table lists the natural communities that are associated with Purple Milkweed. 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 Milkweed. 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 site preparation that heavily disturbs herbaceous ground layer and soil; these include bulldozing and furrowing, as well as grubbing and stump removal.
  • 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

  • Prescribed burns and/or brushing may be beneficial (dependent on local site conditions).
  • Maintain and restore open habitat through selective clearing and brushing.


Purple Milkweed Photo.

Photo © Kitty Kohout.

Purple Milkweed Photo.

Photo by Thomas Meyer, Wisconsin DNR.

Purple Milkweed Photo.

Photo © J.H. Zimmerman.

Purple Milkweed Photo.

Photo © Suzan Campbell.

Purple Milkweed Photo.

Photo by Armund Bartz, Wisconsin DNR.

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