This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol3", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Houstonia purpurea L. Sp. Pl. 105. 1753. Hedyotis purpurea T. & G. Fl. N. A. 2: 40. 1841. Oldenlandia purpurea A. Gray, Man. Ed. 2, 173. 1856. Houstonia purpurea pubescens Britton, Mem. Torr. Club 4: 125. 1894.
Perennial, stout, erect, tufted, branched or simple, glabrous or pubescent, 4'-18' high. Leaves ovate or ovate-lanceolate, sessile, or the lower ones short-petioled, 3-5-nerved and pinnately veined, obtuse or acute,1/2'-2' long, 3"-15" wide, the margins often ciliate; flowers in terminal cymose clusters; pedicels 1"-4" long; corolla purple or lilac, funnel form, 3"-4" long, the tube at least twice as long as the lobes; capsule compressed-globose, 1 1/2" broad, somewhat didymous, its upper half free and considerably shorter than the subulate-linear calyx-lobes.
In open places, Maryland to Iowa, Kentucky, Missouri, Georgia, Alabama and Mississippi, especially in the mountains. May-Sept.
Houstonia ciliolata Torr. Fl. N. U. S. 1: 173. 1824. Houstonia purpurea var. ciliolata A. Gray, Man. Ed. 5, 212. 1867.
Perennial, tufted, erect or ascending, 4-7' high. Lower and basal leaves petioled, thick, 1-nerved, obo-vate or oblanceolate, obtuse, 6"-10" long, their margins conspicuously ciliate; stem leaves oblong or oblanceolate, sessile or nearly so; flowers in corymbed cymes; pedicels filiform, 1"-4" long; corolla funnelform, lilac or pale purple, about 3" long, the lobes about one-third the length of the tube; capsule little compressed, obscurely didymous, 1 1/2" wide, overtopped by the linear-lanceolate calyx-lobes.
On rocks and shores, Ontario to Minnesota, south to Pennsylvania, West Virginia, Kentucky and Arkansas. May-Aug.
Houstonia longifolia Gaertn. Fruct. 1: 226. pl. 49. f. 8.
1788. Houstonia purpurea var. longifolia A. Gray, Man. Ed.
5, 212. 1868.
Perennial, usually tufted, erect, glabrous or pu-berulent, 5'-10' high. Basal leaves spatulate or oblanceolate, obtuse, not ciliate, very short-petioled; stem leaves linear or linear-oblong, acute or obtuse, 1-nerved, 6"-12" long, 1"-21/2" wide; flowers in corymbed cymes; calyx-lobes subulate; corolla pale purple or nearly white, 21/2"-3" long, its lobes about one-third the length of the tube; capsule little compressed, globose, ovoid, about 1" in diameter, its upper half free and much exceeded by the subulate calyx-lobes.
In dry open places, Maine and Ontario to Manitoba, Saskatchewan, Georgia, Mississippi and Missouri. May-Sept.
Houstonia tenuifolia Nutt. Gen. 1: 95. 1818. Houstonia purpurea var. tenuifolia A. Gray, Syn. Flor 1: Part 2, 26. 1878.
Perennial, somewhat tufted, very slender and widely branching, erect, glabrous, 6'-1' high, sometimes finely pubescent below. Basal and lowest stem leaves ovate or oval, obtuse, petioled, 4"-6" long; upper leaves narrowly linear or filiform, blunt-pointed, 6"-15" long, 1/2"-1 1/2" wide; flowers in loose corymbose cymes; pedicels filiform, 2"-6" long; corolla purple, narrow, 2"-3" long, its lobes short; capsule compressed-globose, didy-mous, about 1" in diameter, its upper half free and only slightly exceeded by the subulate calyx-lobes.
In dry soil, Pennsylvania to Ohio, North Carolina and Tennessee. May-July.
Houstonia angustifolia Michx. Fl. Bor. Am. 1: 85. 1803. Oldenlandia angustifolia A. Gray, Pl. Wright. 2: 68. 1853.
Perennial by a deep root, erect, stiff, glabrous, usually branched, 1°-2° high. Leaves linear. 6"-18" long, 1"-3" wide, or the lowest narrowly spatulate, usually with numerous smaller ones fascicled in the axils, or on short axillary branches; flowers in terminal dense cy-mose clusters; pedicels short; corolla white or purplish, between funnel form and salver form, about 2" long, its lobes shorter than the tube; capsule com-pressed-obovoid, \\" wide, its summit free and scarcely-exceeded by the calyx-lobes.
In dry open places, Illinois to Kansas, Texas, Tennessee and Florida. May-July. Star-violet. Venus'-pride.