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Rough Rattlesnake-root (Prenanthes aspera)

Life history

Species overview

Rough Rattlesnake-root (Prenanthes aspera), a Wisconsin Endangered plant, is found in dry prairies, usually on the lower slopes of hills. Blooming occurs late August through early October; fruiting occurs throughout September. The optimal identification period for this species is late August through early October.

Synonyms: Nabalus asperus


  • Distinguishing characteristics: Stem and lower surfaces of leaves rough-hairy; flowers more cream-colored.
  • Flower characteristics: Inflorescence narrow and elongate, raceme-like or a dense panicle; heads crowded, loosely ascending to suberect; flowers 8 to 19 (usually 11 to 14), ochre-colored; pappus straw-like.
  • Fruit characteristics: Achenes elongate, smooth, mostly reddish-brown.
  • Leaf characteristics: Alternate, rough or coarsely covered with short, stiff hairs beneath and often also on the upper side toothed or entire; lower leaves well developed and somewhat obovate, tapering to the petiole, but soon deciduous; upperr leaves sessile or nearly so and often clasping, oblong to elliptic or lanceolate, gradually reduced upward, the larger ones 4 to 11 cm long by 1 to 5 cm wide.


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


  • Growth form: Forb-erect
  • Vegetative reproduction:
  • Life cycle: Perennial
  • Comments: Associated Species: Cirsium hillii, Petalostemum purpureum, Psoralea esculenta, Talinum rugospermum, Parthenium integrifolium, Opuntia sp., Bouteloua curtipendula, Andropogon scoparius.

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 Rough Rattlesnake-root (Prenanthes aspera). 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 Prenanthes aspera in the Natural Heritage Inventory Database as of July 2015.

Summary Information
State StatusEND
Federal Status in Wisconsinnone
State RankS1
Global RankG4?
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 dry prairies, usually on the lower slopes of hills.
  • Soils: Dry soils

Natural communities

This table lists the natural communities that are associated with Rough Rattlesnake-root. 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
Dry Prairie 3
Dry-mesic Prairie 3
Sand Prairie 1

Ecological landscapes

This table lists the ecological landscape association scores for Rough Rattlesnake-root. 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 locating landings, staging areas, or access routes in open sandy areas dominated by native grasses.
  • 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.


Rough Rattlesnake-root Photo.

Photo © Aaron Carlson.

Rough Rattlesnake-root Photo.

Photo © Aaron Carlson.

Rough Rattlesnake-root Photo.

Photo by  staff, Wisconsin DNR.

Rough Rattlesnake-root Photo.

Photo by  staff, Wisconsin DNR.

Rough Rattlesnake-root Photo.

Photo © J.W. Richardson.

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