Herbs perennial. Rhizomes long. Leaves alternate. Inflorescences solitary or several, terminal or axillary in axils of apical leaves, each a broomlike panicle of numerous cincinni; bracts often small. Flowers actinomorphic. Sepals free, shallowly to strongly boat-shaped, leathery, persistent. Petals free, blue or purple, sometimes white, obovate, clawed. Fertile stamens 3 or 6, equal; filaments glabrous; anther locules connate, slightly divergent proximally, ellipsoid, longitudinally dehiscent. Ovary 2-loculed; ovules 1 per locule. Capsule 2-valved, slightly flattened, 1-grooved on each side. Seeds 1 per valve, hemispheric, reticulate or striate; hilum linear.

About 20 species: pantropical; two species (one endemic) in China.