Ruellia strepens aka Limestone Wild Petunia

Ruellia strepens belongs to the acanthus family, Acanthaceae. It is a perennial, so it lives for years. Its common names include wild petunia and smooth ruellia. It is native to the central and eastern United States. It grows across Missouri, which lies within its range. There, it grows in rich, open woods and thickets. It also grows at the edges of streams and ponds. Kew puts it in the temperate climate zone.

This plant forms clumps of soft growth, not a woody frame. Garden plants reach 1–3 feet (0.30–0.91 metres) in height. They spread to about 1.5 feet (0.46 metres). The plant may have no hairs or just a few. Its oval leaves grow in pairs on opposite sides of stems. Each leaf can reach 0.5 feet (0.15 metres) long. The leaves and the clump's shape form a backdrop for blooms.

The blooms look like petunias. Their shades range from pale lilac to lavender. Each flower has five lobes that flare outwards. Flowers reach about 0.17 feet (0.05 metres) in length. They grow in leaf axils, the points where leaves meet stems. The plant blooms from May through September. For gardeners, these showy blooms are its main floral feature. The account gives no details about its fruit or seeds.

In gardens, give this plant part shade and moist soil. It can also grow in almost full shade. Give it soil rich in organic matter that drains well. Its listed water need is moderate, not high. Missouri Botanical Garden says it is easy to grow. It also says the plant needs little upkeep. Its stated hardiness range spans USDA zones 5 through 8. The evidence gives no separate UK hardiness rating.

Wild petunia suits woods, shaded beds, and gardens of native plants. These uses match its need for shade and moist soil. Its long bloom season brings flowers to these sites through summer. Missouri Botanical Garden reports no major pests or diseases. That does not mean each plant will stay free of problems. The sources give no evidence about parts safe to eat. Nor do they say whether the plant is toxic. They give no basis for its use as food or medicine.