Ruellia humulis (Wild Petunia)

Plant Info
Also known as: Fringe-leaf Ruellia, Prairie Petunia, Hairy Wild Petunia
Family:Acanthaceae (Acanthus)
Life cycle:perennial
  • State Special Concern
Habitat:sun; dry sandy or rocky soil; prairie, open woods, rocky slopes, bluffs
Bloom season:June - August
Plant height:8 to 24 inches
Wetland Indicator Status:GP: FAC MW: FACU NCNE: FACU
MN county distribution (click map to enlarge):Minnesota county distribution map
National distribution (click map to enlarge):National distribution map

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Detailed Information

Flower: Flower shape: 5-petals Flower shape: tubular Cluster type: whorled

[photo of flower] 1 to a few stalkless flowers in the upper leaf axils. Flowers are funnel-shaped, about 1 inch across and 1½ to 2½ inches long, lavender to pinkish or pale blue, with 5 widely spreading lobes and darker lines inside the throat. Inside the tube are 4 white to purplish stamens and a white to purplish style with a divided tip.

[photo of calyx and floral tube] The tube is contracted one third to halfway down its length, becoming very slender, pale greenish and stalk-like. The calyx surrounding the base of the flower has 5 linear lobes about half as long as the constricted part of the tube, the lobes with long, spreading hairs around the edges.

Leaves and stems: Leaf attachment: opposite Leaf type: simple

[photo of leaves and stems] Leaves are 1 to 3 inches long and up to 1 inch wide, toothless, densely hairy, lance to nearly diamond-shaped, with a blunt point at the tip, and stalkless or nearly so.  Attachment is opposite, with pairs at right angles to the pair above and below. Edges are somewhat wavy. Stems are erect, single or multiple from the base, few-branched, weakly 4-sided, green to purplish, and variously covered in long, spreading, white hairs.

Fruit: Fruit type: capsule/pod

[photo of fruit] Fruit is a smooth, 2-sectioned, bullet-shaped capsule that is shorter than the calyx lobes. Each section contains 3 to 8 flattened oval seeds that are ejected when ripe.

[photo of dry and wet seed] Seeds are covered with fine, spiraling hairs that unwind when wet, burying the seed in the soil.


An Endangered Species in 1984 but long thought extirpated from Minnesota, a new population of Wild Petunia was discovered at Afton State Park in Washington County in 2005. According to the DNR, the area where it was found was formerly pasture so it is unknown if this population is naturally occurring or introduced. Since the Afton population is still the only known occurrence in the state, it was designated a Special Concern species in 2013; that status may change if additional locations are found. It is currently listed as Endangered in Wisconsin. Wild Petunia is increasingly available in the native plant trade and does well in cultivation.

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More photos

Photos courtesy Peter M. Dziuk taken in his backyard garden in Ramsey County.


Have you seen this plant in Minnesota, or have any other comments about it?

Posted by: Desmond - Welch 55089
on: 2016-05-28 01:00:46

I spotted a few of these in the woods behind my home.

Posted by: Garrett M - Saint Cloud
on: 2016-11-22 12:34:03

Wow Desmond you live a crazy life.

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