Epiphytic, usually growing on ant-nests, caulescent, pendent, repent, to erect herbs, shrubs, or lianas, without modified stems. Stems branched or unbranched. Leaves opposite, equal to rarely strongly unequal in a pair, venation pinnate, foliar nectaries present on lower leaf surface. Flowers axillary, solitary or in cymose few-flowered inflorescences; epedunculate or very short-pedunculate; bracteoles absent; short pedicellate. Calyx lobes 5, nearly free or briefly connate at base, or united into 2 lobes (C. calcarata); corolla white, pink, lilac, yellow, or deep purplish, often with reddish lines or spots, funnel-shaped to subcampanulate, limb 5-lobed; stamens included, filaments basally connate, anthers coherent in pairs by tips or sides, later separating, dehiscing by apical pores, thecae separated by broad connectives; staminode very small; disc a single dorsal, usually large gland; ovary superior, stigma stomatomorphic to 2-lobed. Fruit a fleshy, indehiscent, red, pink, orange, or yellow-green berry (in Guianan species).
Guianas: present Lesser Antilles: present Northern America: Southern America:, Bolivia (Bolivia ‒ present); Peru (Peru ‒ present)
A genus of 15 species from Mexico to Brazil, and from the Lesser Antilles to Peru and Bolivia, on arboreal ant-nests in rainforests; 2 species in the Guianas.
Plants are usually associated with ants in various ways; growing from or on arboreal ant-nests, and often with extrafloral nectaries on the underside of the leaves, between the bases of the calyx lobes, or at the nodes. The colored seeds are covered by a gelatinous aril or have a funicle that may be associated with ant dispersal.