Annual or rhizomatous perennial herbs; corm usually short and thick. Leaves distichous in basal rosette, linear or ensiform, firm, closely ribbed. Inflorescence of various arrangement; outer bracts wholly or partially firm; inner ones membranous, brown or white, often lacerated; flowers blue, clustered, appearing in succession; perianth segments ± equal in length, spreading; twisting spirally after flowering; stamens free, inserted in tube, anther erect, linear-oblong; ovary oblong to clavate; style thread-like, stigmatic lobes 3, very short, spreading, flattened. Capsule oblong to cylindric, rigid.
About 60 species of southern and tropical Africa, and Madagascar Is.; 2 species have become naturalised in Australia.