Slender perennial herbs from scaly rhizomes; stems short, unbranched, hir-sute or villous. Leaves opposite, nearly equal in a pair, membranous, coarsely crenate, dentate, or serrate; petioles usually elongate. Inflorescences axillary or terminal racemes, pedunculate, bracteate. Flowers few; floral tube turbinate; calyx 5-lobed, each lobe free, elongate, often spreading, entire, green; corolla white, sometimes with purple markings, tubular, funnelform or cylindric, erect in the calyx, neither spurred nor ventricose, only slightly broader toward the limb, the limb of 5 rounded lobes, terminal, regular or slightly bilabiate; stamens 4, with a small staminode, the filaments adnate to the base of the corolla tube, the anthers orbicular, at first coherent by their apices, later discrete, thecae slender, dehiscent by slits above; disc of 5 glands sometimes connate into 2-3 glands; ovary 1/2-inferior; style elongate, slender, the stigma bibbed. Fruit an obovoid capsule, membranous, the apex convex, 2-valved; seeds numerous, minute.
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