Limestone Ruellia is a perennial herb, 1-3 ft tall. Oppositely arranged stalked leaves are ovate, ovate-lanceshaped, to oblong, typically entire or merely crenulate, up to 15 cm long, 6 cm wide. Leaf stalks is typically winged. One or two flowers arise on a stalk from leaf axils near the middle of stem. Flowers are subtended by a pair of leaf-like bracts. Flowers are up to 5 cm long, 4cm broad, with 5 petals, typically blue or pinkish blue. Flowers have a a constricted portion at base, which is white, up to 2.5 cm long, 3 mm in diameter. Expanded portion of the flower tube is up to 1 cm long, 1 cm in diameter. Petals are 1.5 cm long and broad. Stamens are 4, as in all Barleria family flowers. Flowering: May-October.