Perennial, rhizomatous herbs or shrubs with frequently twining or climbing stems. Leaves alternate, usually petiolate, cordate or hastate at base, entire. Flowers axillary, pedicellate, variously coloured, sometimes variegated. Perianth zygomorphic, lower part of tube (utricle) swollen around the style, upper part more or less cylindrical, narrowing, straight or variously curved, ending with entire, lobed or appendiculate limb. Stamens mostly 6, with more or less sessile anthers adnate to the stylar column. Ovary inferior, (4-)6-celled, many-ovuled; stylar column composed of (4-)6 or more styles and as many stigmas. Capsule septicidal, usually dehiscent into 6 valves. Seeds many in 1 row, compressed.