Description from Flora of China
Perennials. Stems elongated and twining or prostrate and creeping, rarely erect in some individuals. Leaves opposite. Inflorescences axillary and terminal, 1-flowered or in cymes. Flowers 5-merous. Calyx tube usually with 5 keeled ridges. Corolla tubular or broadly tubular, plicae present. Stamens inserted at basal part of corolla tube, unequal, apically recurved. Nectaries conspicuously developed, forming a collarlike disc surrounding base of ovary. Ovary 1-locular; ovules many. Style slender, slightly recurved; stigma linear, recurved at anthesis. Fruit a capsule or berry, many seeded. Seeds triquetrous to compressed, winged or wingless.
About 25 species: E and S Asia; 19 species in China.
Some species of Tripterospermum are very similar in flower, and fruit with seeds may be necessary for positive identification.