Description from Flora of China
Lianas. Inflorescences terminal or extra-axillary, umbel-like, paniculate, or racemelike, pedunculate. Sepals overlapping, basal glands or scales often present. Corolla urceolate or campanulate, throat often hairy; lobes twisted to right. Corona lobes 5, erect, acuminate, fleshy, attached to gynostegium. Filaments connate into a tube; anthers erect, appendages inflexed; pollinia 2 per pollinarium, often oblong, erect. Stigma head flat, convex, or beaked. Follicles mostly thick, acuminate, smooth or longitudinally winged.
About 100 species: Asia, America, tropical Africa; 25 species in China.