Herbaceous to woody vines. Stems tereteand lenticellate, becoming 3-lobed with age, producing milky sap; cross section with a single vascular cylinder. Stipules minute, deciduous or persistent. Leaves trifoliolate or less often biternate; petioles or rachis unwinged. Inflorescence a thyrse with closely spaced cincinni. Flowers zygomorphic, bisexual. Calyx of 5 sepals; petals 4, distinct, usually < 4 mm long, spatulate, with an adnate, hood-shaped appendage on adaxial surface; disk unilateral, 4-lobed, receptacle enlarged into a short androgynophore. Stamens 8; filaments unequal; anthers sometimes with an apical appendage. Ovary of 3uniovular carpels; style distal with 3 stigmatic branches. Fruits thin, papery, semi-inflated capsules, with narrow marginal wing. Seeds subglobose, black, with a heart-shaped or reniformwhite arillode around the hilum; embryo with the abaxial cotyledon bent over the biplicate adaxial cotyledon.