Annual or perennial climbing herbs, stems ridged. Stipules small, caducous. Leaves alternate, compound (2-ternate to apparently pinnate). Inflorescence axillary, at the apex of a relatively long peduncle, with a pair of coiled tendrils just below. Flowers zygomorphic. Bracts minute. Sepals 4; lateral small, the other 2 larger. Petals 4. Stamens 8. Ovary 3-locular. Fruit an inflated membranous capsule. Seed black with a white, ovate to reniform (sometimes ± heart-shaped) hilum.