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Hairy Wild Petunia (Ruellia humilis)

Life history

Species overview

Hairy Wild Petunia (Ruellia humilis), a Wisconsin Endangered plant, is found in prairies and upland oak woods. Blooming occurs late May through early October; fruiting occurs late June through early October. The optimal identification period for this species is late May through early October.

Synonyms: Ruellia ciliosa var. longiflora, Ruellia humilis var. calvescens, Ruellia humilis var. depauperata, Ruellia humilis var. expansa, Ruellia humilis var. frondosa, Ruellia humilis var. humilis, Ruellia humilis var. longiflora


  • Distinguishing characteristics: Distinguished by its profusion of hairs, sessile or subsessile leaves, narrowly linear calyx lobes and a long funnelform lavender flowers.
  • Flower characteristics: Flowers in sessile or subsessile, crowded cymose clusters from the axils of several upper leaves; calyx lobes less than 1 mm wide; corolla blue-lavender, 3 to 7 cm, funnelform, 5-lobed; stamens 4, weakly united in pairs toward the base, the lower pair somewhat longer.
  • Fruit characteristics: Smooth.
  • Leaf characteristics: Opposite, sessile or subsessile, 3 to 8 cm long, acute to very obtuse; margins hairy.


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


  • Growth form: Forb-erect
  • Vegetative reproduction:
  • Life cycle: Perennial
  • Comments: Associated Species: Andropogon scoparius, Euphorbia corollata, Lithospermum canescens, Petalostemum purpureum, Ratibida pinnata, Lespedeza capitata, Helianthus occidentalis.

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 Hairy Wild Petunia (Ruellia humilis). 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 Ruellia humilis in the Natural Heritage Inventory Database as of July 2015.

Summary Information
State StatusEND
Federal Status in Wisconsinnone
State RankS2
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 prairies and upland oak woods.
  • Soils: Sandy, loamy soils.

Natural communities

This table lists the natural communities that are associated with Hairy Wild Petunia. 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

Ecological landscapes

This table lists the ecological landscape association scores for Hairy Wild Petunia. 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 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.
  • Avoid broadcast spraying of herbicides; use care with spot spraying.

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.


Hairy Wild Petunia Photo.

Photo © Julie Robson.

Hairy Wild Petunia Photo.

Photo by Thomas Meyer, Wisconsin DNR.

Hairy Wild Petunia Photo.

Photo by Thomas Meyer, Wisconsin DNR.

Hairy Wild Petunia Photo.

Photo © John Zaborsky.

Hairy Wild Petunia Photo.

Photo by Ryan Clemo, 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