Annual or perennial herbs, not twining. Leaves simple, entire, usually ± sessile. Inflorescences of axillary, 1-few-flowered cymes. Sepals subequal. Corolla broadly funnel-shaped. Stamens 5. Ovary ovoid or spherical, 1-2-locular. Styles 2, quite or almost separate, each style forked for about half its length. Capsule 2-4-valved. Seeds 4 or fewer, glabrous.
Worldwide: 98 species in warm and tropical America; 2 extending to the Old World.