The Limestone wild petunia (Ruellia strepens) belongs to Acanthaceae (the Acanthus family). It is a perennial herb that is distributed from the eastern to south-central parts of the United States, and from Pennsylvania to Kansas and Texas. This herb grows in bright forests, wastelands, and riverbanks, and is about 1 m high. The stem is upright and almost hairless. The leaves are ovate to ovate lanceolate, oblong and opposite, and the petioles usually have wings. From May to October, one or two blue or white tubular flowers come from the axils. The tip of the corolla splits into five.