Description from Flora of China
Shrubs or small trees, sometimes scandent, pubescent or glabrous. Leaves simple; stipules subulate, caducous; leaf blade elliptic or ovate, entire or 3-5-lobed, base truncate or cordate, margin crenate to dentate; foliar nectaries lacking. Flowers solitary, axillary, or sometimes in terminal cymelike clusters. Epicalyx lobes 5-10(-12), linear, lanceolate, or spatulate. Calyx campanulate or tubular, 5-lobed. Corolla tubular; petals 5, red or crimson-red, bases auriculate, remaining adpressed to staminal column. Filament tube longer than corolla, apex 5-toothed; anthers below teeth, on outside of staminal column only. Ovary 5-loculed; ovules 1 per locule; style branches 10; stigmas capitate. Fruit a fleshy schizocarp, usually red (sometimes white), broader than long, ultimately drying and separating into mericarps; mericarps 5, indehiscent. Seeds 1 per carpel.
The genus is highly variable morphologically, with many populational forms that intergrade. This variation has led to widely differing opinions as to the number of species and subspecific taxa. The classification adopted here is a conservative one and follows the revision of Turner and Mendenhall (Ann. Missouri Bot. Gard. 80: 439-457. 1993).
About five species: native to tropical America, but several now widely cultivated; two species (both introduced) in China.