Description from Flora of China
Alexitoxicon Saint-Lager; Antitoxicon Pobedimova; Cyathella Decaisne; Cynoctonum E. H. F. Meyer; Pycnostelma Bunge ex Decaisne; Rhodostegiella C. Y. Wu & D. Z. Li; Seutera H. G. L. Reichenbach; Symphyoglossum Turczaninow; Vincetoxicum N. M. Wolf.
Subshrubs or perennial herbs, erect or twining, often rhizomatous. Roots fibrous, woody or fleshy. Leaves opposite, rarely whorled, often petiolate, axils sometimes with small stipulelike leaves. Inflorescences extra-axillary or occasionally terminal, rarely axillary, umbel-like, corymbose, or racemelike. Sepals erect, often with basal glands. Corolla rotate or subrotate; tube short; lobes patent or reflexed, overlapping to right or left, rarely subvalvate. Corona inserted at base of gynostegium, membranous or fleshy, cupular, cylindric, or deeply 5-divided, sometimes with adaxial appendages. Filaments connate into tube, anthers with membranous apical appendages; pollinia 2 per pollinarium, pendulous. Stigma head convex or short conical. Follicles fusiform or lanceolate, usually smooth, rarely narrowly winged or setose.
About 200 species: Africa, North and South America, Asia, Europe; 57 species in China.