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.

Posted by: Karen L - Rural St Cloud
on: 2018-07-11 23:09:32

Saw a white version by Pleasant Lake near St. Cloud growing extensively by the boat launch parking lot for the lake. We were canoeing there this morning. Certainly didn't look endangered. Was a vine that wrapped around many of the weeds in the area. Leaves match the description. Flowers look more like a typical petunia, so maybe a variation?. I wasn't aware there was a "wild" petunia. Any ideas?

Posted by: K. Chayka
on: 2018-07-12 07:42:05

Karen, wild petunia is not a vine. What you saw was either the native morning glory, Calystegia sepium (hedge bindweed) or the weedy Convolvulus arvensis (field bindweed).

Posted by: Kylene O - Chippewa County-western MN
on: 2018-11-07 08:07:51

About 10 years ago I bought a wild petunia plant at a native plant nursery. It has become very prolific in my yard, reseeds easily. Comes up in the lawn and along the edge of flower beds. Flowers even when very short in the lawn. I really enjoy this plant.

Posted by: Doreen Bower - Carver County
on: 2019-07-14 16:26:06

I deeply regret planting this. I bought it at a native nursery 8 years ago. It pops up everywhere and crowds out other native plants. The roots are tough and must be dug out. I'm hoping I can eliminate it over multiple years.

Posted by: K. Chayka
on: 2019-07-14 20:57:58

We have wild petunia in our gardens. It moves around a bit but it has lots of competition to keep it in check so hasn't become a pest.

Posted by: Ellie Anderson - Washington County
on: 2019-08-12 12:01:51

Just found this my garden, August 2019. It is all by itself among sedum groundcovers and 'Autumn Joy.' A rare find!

Posted by: Diana Cumming - NE Minneapolis
on: 2020-07-02 07:43:09

I planted this is my yard many years ago and it mixes in with the asclepius tuberosa, the liatris species, lobelia, and everything else. Lovely plant. Fine among the blue flag irises that die back as the heat arrives.

Posted by: Freddie - Minneapolis
on: 2020-07-24 13:56:18

I planted a few of these in 2015. I thought the rabbits ate them all, but it came back and is now flourishing. In some areas, I'm going to have to pull some of it, as it seems to be taking over. I checked here, wondering if it was spreading by rhizomes. Glad to know otherwise. because as I understand it, that's how plant populations choke out other species. (And rhizomes are a bugger to remove.) It's also sprouting up in my lawn and other gardens in the yard. The fruit, as shown here, seems like it wouldn't go airborne, so my guess is the squirrels and birds are spreading it. (Sprouting in areas within a rabbit-proof fence.) At any rate, it's interesting to know that it's been endangered. Perhaps I'll share the fruit with some neighbors to help with its comeback. Love the website. Thanks!

Posted by: Josh Yank - South Minneapolis
on: 2021-09-04 20:04:43

There are a few in the native plantings on the east side of lake Nokomis. The blooms really stand out, but don't seem to last long (at least at this time of year (late summer/early fall)).

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