Perennial herb with fibrous roots 10 cm - 0.5 m tall Leaves: opposite, stalkless, 2 - 5 cm long, 0.5 - 3 cm wide, egg-shaped to oblong lance-shaped with a rounded or almost heart-shaped base, three- to five-veined, hairless or nearly so. Inflorescence: a terminal cluster (cyme) of many small flowers. Flowers: short-stalked, purple to lilac to white, 5.5 - 9.5 mm long, funnel-shaped, hairy within, with four lobes. The tube is twice as long as the lobes. Stamens included or barely exserted. Style one, stigmas two. Fruit: a small, dehiscent capsule, 2.5 - 3.5 mm wide, more or less spherical. Stems: several, upright, slender, unbranched or branched above, sometimes hairy.

Similar species: Houstonia longifolia is similar but its lower leaves are strictly one-veined.

Flowering: May to June

Habitat and ecology: Rare, if at all occurring, in the Chicago Region. Has been found in a field and may occur in woods.

Occurence in the Chicago region: native

Etymology: Houstonia is named after Dr. William Houston (1695-1733), a Scottish-born surgeon and botanist who collected plants in Mexico and the West Indies. Purpurea means purple. Calycosa means "remarkable covering."

Author: The Morton Arboretum