Rhizomatous herbs or shrubs, with much branched, mostly climbing or twining stems. Leaves alternate, petiolate, simple, generally cordate at base, entire, exstipulate. Flowers hermaphrodite, axillary, solitary or racemose, actinomorphic or zygomorphic, usually 3-merous. Perianth simple, petaloid, forming a tube with 3 lobes or with a unilateral limb. Stamens 6-36, in 1-2 whorls; the anthers and filaments free or adnate to the stylar column (gynostemium). Ovary usually inferior, 4-6-carpelled, with numerous anatropous ovules; placentation axile; styles 3 to many, free or united into a column with a 3- to many-lobed stigma. Capsule dehiscent or rarely indehiscent. Seeds many; endosperm copious; embryo minute.