Plants mostly epiphytic. Old stems woody at base, often terete; branches usually flattened and leaflike, or 3-winged, with stout midrib, margins crenate, coarsely serrate, or lacerate, sometimes horny. Areoles seated between crenations of stem margins, woolly when young, setose in juvenile growth. Leaves and spines absent. Flowers nocturnal, borne in lateral areoles, solitary, sessile, funnelform or salverform, usually large. Receptacle tube elongate, with scattered scales. Perianth spreading to rotate; segments usually linear-lanceolate. Petaloids white; outer ones often recurved, sometimes cream or pinkish. Stamens numerous; filaments inserted in receptacle tube and perianth throat; anthers exserted. Placentas parietal; style elongate; stigmas numerous, exserted, linear. Fruit green, red, or purplish, globose to cylindric, usually fleshy, with low ridges bearing scales, usually splitting along one side when ripe. Seeds numerous, ovate-reniform; testa glossy black, minutely wrinkled or spotted.
About 13 species: tropical America; four species cultivated in China as ornamentals, of which one species occasionally escaped from cultivation in tropical areas.