Description from Flora of China
Baoulia A. Chevalier; Dichaespermum Wight; Dilasia Rafinesque, nom. rej.; Phaeneilema Brückner; Prionostachys Hasskarl; Streptylis Rafinesque, nom. rej.
Herbs perennial, sometimes annual. Roots often fusiform thickened. Rhizomes present or absent. Stems creeping or ascending, sometimes scapiform. Leaves alternate and linear, or in a basal rosette on infertile main stems. Cincinni solitary or numerous, forming panicles, sometimes shortened into heads, sometimes reduced to solitary flowers. Flowers actinomorphic. Sepals free, shallowly to strongly boat-shaped. Petals free, purple, blue, pink, yellow, or nearly white, orbicular or obovate. Fertile stamens 3, sometimes 1(or 2) abortive; filaments glabrous or hairy; anther locules longitudinally dehiscent; staminodes (absent to)3(or 4), inserted opposite petals; antherodes sagittate or 3-sect. Ovary 3-loculed; ovules 1--7 per locule. Capsule 3-valved, ovoid, ellipsoid, or globose. Seeds 1 or 2 per valve, uniseriate, quadrangular, reticulate, pitted, rugose, or verrucose; hilum orbicular.
About 50 species: tropical and subtropical regions, mainly in Asia; 20 species (six endemic) in China.