Ruellia caroliniensis aka Carolina Wild Petunia

Ruellia caroliniensis is a perennial wildflower in the Acanthaceae family. Gardeners know it as Carolina wild-petunia or wild petunia. It comes from the central and eastern United States. In North Carolina, it grows in lawns, woods, and forests. Its woodland habitats range from dry sites to moist ground. It occurs across the state's coastal, piedmont, and mountain regions.

The plant grows upright, with stems that do not branch. Garden plants reach 1–3 feet (0.30–0.91 metres) tall. Their spread is about 0.5–1 foot (0.15–0.30 metres). The green leaves grow in opposite pairs along the stems. Each leaf has an oval to egg-shaped outline. Leaves sit close together, giving the stems a crowded look. The leaves lack hairs, while the stems have hairs. The stems have no scent.

Flowers appear from May through September, spanning spring into fall. Their shades range from blue to purple and pale lavender. Each trumpet-shaped flower has a narrow tube and five spreading lobes. Groups of three or four flowers form at the leaf axils. These are the points where leaves meet the stem. The flowers have no stalks of their own. Only one or two flowers in a group open each day. Each bloom lasts one day, but flowering continues for months. Fruit develops from June through October. Hooked structures within the fruit hold the seeds.

In gardens, this species suits part shade and sandy, acid soil. It grows in moist soil and tolerates ground that dries sometimes. Its care needs are low. Growers can raise new plants from seed or stem cuttings. It also sets seed freely without help. That trait can make it an unwanted plant in lawns. Southern blight is a disease problem listed for this species.

Wild petunia fits butterfly gardens and gardens planted for pollinators. Its long bloom season adds color over several months. The flowers attract butterflies and other pollinators. Common buckeye caterpillars use the plant as a leaf food source. In North Carolina, this butterfly has two or three broods from May through October. The plant also supplies food for songbirds. Its wildlife role extends beyond the short life of each flower.