Annual or perennial herbs or small climbers, rarely shrubs, glabrous or hairy, with or without tendrils. Leaves lobed or not, sessile or petiolate; margin entire or usually dentate with small glandular teeth. Stipules small, linear. False stipules present in some species, developed from the supra-axillary bud. Tendrils axillary, replacing central flower of cyme, or absent. Inflorescences axillary, cymose, 1–3-flowered, sessile or peduncled; bracts and bracteoles small, linear, often forming an involucre. Flowers bisexual (sometimes functionally unisexual), campanulate, greenish. Stipe indistinctly articulate at base to the short pedicel. Hypanthium rather narrow, flattish, rarely shallowly cup-shaped. Sepals 5(–6), oblong to lanceolate, free. Petals absent, 1–2 or (4–)5(–6), oblong to lanceolate, obtuse or subobtuse, free, usually smaller than the sepals. Outer corona consisting of a ± barrel-shaped tube bearing a ring of filiform processes (threads), bluish and mostly with a ring of small inward curved teeth. Disk low, annular, rarely absent. Inner corona membranous, cup-shaped, margin entire or lobulate (in B. berberoides from Somalia forming 5 small cups around the bases of the filaments). Stamens 5(–6–9); filaments inserted in the upper half inside the inner corona, free; anthers basifixed, ellipsoid to lanceolate, subsagittate, 2-thecous. Ovary ellipsoid, superior, usually sessile, 1-locular, with 3(–4) placentas; styles 3(–4), free or partially united; stigmas globose, small. Fruit a sessile or shortly stiped 3(–4)-valved capsule, ellipsoid; valves coriaceous. Seeds 1-few, arillate, ellipsoid to reniform, ± compressed; testa coriaceous, mostly rugose, blackish.