Perennial herbs. Leaves alternate, with a basal closed sheath. Flowers regular or slightly irregular, bisexual. Sepals 3, usually green. Petals 3, free or rarely connate. Stamens 6 or sometimes 2–3 with 3–4 staminodes, free, hypogynous. Ovary 3-locular; placentas axile; style filiform. Fruit a capsule or nut. 40 gen., trop. to warm temp.