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Perennial herbs or shrubs. Stems erect, procumbent or clambering, pubescent or occasionally glabrous. Leaves petiolate, opposite pair connected by transverse ridge; blades narrowly lanceolate to ovate, margin entire or somewhat dentate. Inflorescences terminal or axillary racemes, these lax or dense, often secund, flowers single or paired, pedicels short; bracts 2, small, linear to narrowly deltoid; bracteoles 2, similar to bracts. Calyx 5-lobed, lobes linear-setaceous or lanceolate, subequal; corolla more or less regular, infundibuliform, limb 5-lobed, purplish, blue, yellow, or white, tube short to long, funnelform, ventricose or narrow, throat ampliate or campanulate, lobes 5, equal, spreading, imbricate in bud, abaxial lobe with a palate in form of longitudinal fold; stamens 4, inserted in pairs in widened part of corolla tube, included, didynamous, or occasionally posterior ones reduced to filiform staminodia, anthers 2-thecous, thecae parallel, inserted equally, approximate, minutely spurred or muticous at base; disk cupulate or annular; ovary with 2 ovules per locule, style long, subulate, stigma thickened, obtuse or minutely 2-lobed or subcapitate. Capsules stipitate, pubescent, elliptic, base contracted and solid, lacking seeds, retinacula present, septae with retinacula remaining attached to inner wall of mature capsule; seeds 2 or 4, ovate or compressed orbicular, irregularly angular, rugose or tuberculate.


Africa present, Asia-Tropical: India present, East Indies present, Guianas present, New World tropics, Old World tropics present
Old World tropics, chiefly in the East Indies, India and Africa, and now thoroughly naturalized in the New World tropics; around 40 species, 1 in the Guianas either as cultivar or escape.