Erect herbs (rarely prostrate in C. purpurascens) to subshrubs. Leaves sessile to shortly petiolate, petioles 0.2-2 cm long; secondary veins 2-4(-6). Inflorescences terminal cymes, with 1-2 dichasial branching points terminating in 2 or more monochasial branches; bracts and bracteoles scale-like (sometimes leaf-like when subtending most basal flower). Flowers pedicellate, 5-merous, zygomorphic; calyx fused for 1/6-4/5 of total length, coriaceous, campanulate, lobes with thickened, glandular dorsal area, circular, ovate, elliptic to obovate, not winged or keeled (small wings present in C. hamatus), (upward-facing hook protruding from apex of glandular area in C. hamatus), apex obtuse; corolla bud apex rounded; corolla fused for 3/5-6/7 of total length, thin, campanulate, funnel-shaped, tubular to salver-shaped, 18-87 mm long; androecium zygomorphic with stamens and style bent toward bottom of corolla mouth (in C. pterocaulis stamens and style are clustered together in corolla throat); stamens inserted near base of corolla at 1/6-5/8 of corolla tube length (just above midpoint in C. grandiflorus), of subequal to unequal length, filament base without specialized structures (in C. grandiflorus staminal gaps sometimes present and in C. hamatus corona present), anthers elliptic to slightly ovate, obovate, or oblong, with apical sterile appendage, pollen in tetrads (polyads in C. purpurascens); pistil with nectary disk; stigma bilamellate. Fruit a capsule, with persistent calyx and persistent, partly persistent, or deciduous corolla; seeds angular-cuboidal, 0.1-0.6 mm in diam., testa cells dome-like and/or concave with or without band-like thickenings.
Amazon Basin: present Andes from Venezuela to Bolivia: present Brazilian Highlands: present Caribbean islands of Trinidad and Grenada: present Guayana Highlands: present Guianas: present NE Argentina: present S Mexico: present S and C America: present Southern America:, Paraguay (Paraguay ‒ present)
10 species in S and C America (1 species to S Mexico), Caribbean islands of Trinidad and Grenada, the Andes from Venezuela to Bolivia, Guayana Highlands, Brazilian Highlands (1 species to Paraguay and NE Argentina), Amazon Basin; 7 species in the Guianas.