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. May be found in woods and fields.
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.
Author: The Morton Arboretum
From Flora of Indiana (1940) by Charles C. Deam
My specimens are mostly from the southern half of the state where it is more or less frequent and occurs mostly on slopes in white and black oak woods. In the northern part of the state it has been reported from Cass, Kosciusko, Lake, and Tippecanoe Counties. This species, like Houstonia longifolia, is extremely variable. I have specimens with the leaves varying from narrowly lanceolate to broadly ovate. The calyx lobes vary from 3-6 mm in length. The plant that has the widest leaves has the longest calyx lobes. The plants are more or less pubescent and an extreme form which is densely pubescent all over is f pubescens (Britt.) Fern. (Rhodora 38: 444. 1936.) I have the form from Perry and Pike Counties.