Climbers; stems sometimes with corky protuberances. Leaves opposite; those of a pair equal. Inflorescence terminal and/or axillary, often thyrsoid; flowers 5-merous. Sepals with or without colleters in the axils. Corolla lobes dextrorse in bud, asymmetrical with a slant to the right; tube cylindrical or somewhat inflated, widening at the point of stamen insertion and somewhat constricted at throat; mature corolla salverform. Stamens inserted at around the middle of the corolla tube, completely included within the tube, adnate to the style head; filaments short; anthers fertile in the upper half only, the lower half sterile, laterally with lignified guide rails and sagittate appendages at the base. Disk of 5 lobes or in a ring, shorter than the ovaries. Gynoecium 2-carpellate, apocarpous but apically united into a common style, pubescent (in Malesia); ovules numerous; style head cup-shaped. Fruit of paired follicles; linear and narrow; pubescent or glabrous. Seeds not beaked; narrowly ovate or linear; glabrous; with an apical coma.
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