Wild petunia's funnel-shaped, 5-lobed flowers look something like the petunias you find at garden centers, but it is not related to them. It grows statewide in a variety of habitats.
Wild petunia is a perennial, either single-stemmed or branched.
The stems can be smooth or (more commonly) slightly hairy in 2 narrow, lengthwise bands on opposite sides of the stalk, the hairs appearing crinkled. The stems are bluntly 4-angled.
The flowers are few, arising from nodes near the middle of the stems, tubular with 5 lobes, resembling petunia flowers; they are lavender to lilac-blue, very rarely white.
Blooms May–October.
The leaves are opposite, on short stalks, and ovate.
Similar species: There are 2 other wild petunias in our state, both of which have stems that are evenly hairy on all sides:
- Hairy wild petunia (or fringeleaf ruellia, Ruellia humilis) is scattered nearly statewide, has leaves that are stalkless or with only very short stalks, and has flower clusters in the axils of the main stem leaves.
- Stalked wild petunia (Ruellia pedunculata) is scattered in the Ozarks and Ozark Border, has leaves with definite stalks, and has flower clusters in axils of small leaves at the tip of inflorescence stalks.
Height: to 3 feet.
Scattered nearly statewide.
Habitat and Conservation
Occurs in bottomland forests, rich upland forests, banks of streams and rivers, edges of ponds and lakes; less commonly in bottomland prairies and fens; also in pastures, moist roadsides, and railroads.
Status
Native Missouri wildflower.
Human Connections
With its showy flowers, wild petunia is an interesting native choice for the gardener. A clump-forming plant, it's easily grown in moist, rich, well-drained soils in part shade. Try it in woodland, shade, or native-plant gardens. Please don't dig them from the wild; buy them at a reputable native plant nursery.
Ecosystem Connections
Many species in the acanthus family produce two kinds of flowers: some that are open-flowering, which can be cross-pollinated by insects, and others that never open, which self-pollinate yet produce viable seeds. Either way, seeds can be produced.
Our state has three Ruellia species, but there are about 250 species in the world. Most of them are in tropical and warm-temperate regions.
Relatives and lookalikes: Do not confuse these with the petunias that are so popular at garden centers; those are mostly hybrids in the genus Petunia, which is in the Solanaceae (the family containing potatoes, tomatoes, nightshades, chili and bell peppers, and so on). Those "true" petunias originated in South Africa and are quite unrelated to our "wild petunias."
- Our wild petunias, in the acanthus family, are more closely related to many tropical plants, including the houseplants called "nerve plants" and "polka dot plants," and garden plants in the genera Justicia (such as Brazilian plume and shrimp plants) and Thunbergia (black-eyed Susan vines).
