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..
Erect or procumbent perennial herbs or shrubs, with entire leaves (smaller ones some-tibes fascicled in their axils), and blue or purple, rather large, bracted flowers, axillary, solitary or clustered. Calyx deeply 5-cleft, the lobes setaceous. Corolla funnelform, the tube slightly curved, enlarged above, or cylindraceous, the limb spreading, 5-lobed, somewhat 2-lipped, the lobes rounded, sinistrorsely convolute in the bud. Stamens 4, didynamous, included, all anther-bearing in our species; anther-sacs mucronate at the base. Ovules 2 in each cell of the ovary; summit of the style recurved; stigma simple, or of 2 unequal lobes. Capsule oblong, linear, narrowed at the base, 2-4-seeded, in some species coherent. Seeds flat, orbicular, attached by their edges to the retinacula. [Greek, referring to the coherent capsule-valves.]
About 30 species, of wide distribution in warm and tropical regions. Besides the following, 4 others occur in the southern and southwestern United States. Type species: Dyschoriste depressa Nees.
Ruellia biflora L. Sp. Pl. 633. 1753 ?
R. oblongifolia Michx. Fl. Bor. Am. 2: 23. 1803.
Calophanes oblongifolia Don; Sweet, Brit. Fl.
Gard. (II.) pl. 181. 1833. Dipteracanthus biflorus Nees, Linnaea 16: 294.
1842. D. oblongifolia Kuntze, Rev. Gen. Pl. 486. 1891.
Rootstocks horizontal, slender; stems slender, erect, simple, or branched below, pubescent or puberulent, obtusely 4-angled, 6'-15' high, rather stiff. Leaves ascending or erect, oblong or oval, rounded at the apex, somewhat narrowed at the base, very short-petioled, or sessile, pubescent or glabrate, 8"-15" long; flowers commonly solitary in the axils; calyx-segments filiform, hirsute, exceeding the oblong, obtuse bractlets; corolla blue, or mottled with purple, 8"-12" long, slightly 2-lipped, its tube enlarged above; capsule oblong, about one-half the length of the calyx; anther-sacs mucronate-aristate at the base.
In sandy pine barrens, Virginia to Florida, mainly near the coast. June-Sept.