smooth ruellia

Ruellia strepens, commonly known as limestone wild petunia, limestone ruellia, smooth wild petunia, or wild petunia is a species of flowering plant in the family Acanthaceae, native to warmer parts of the central and eastern United States. A perennial herb, it prefers to grow in moist to mesic, partly shady areas such as streamsides and bottomland forests. In the garden it is hardy to USDA zone 5, and can tolerate nearly full shade.