Herbs perennial, climbing or suberect. Rhizomes absent. Lateral branches penetrating leaf sheaths. Leaves alternate. Inflorescence borne opposite leaf and exserted from mouth of leaf sheath, but not penetrating sheath, a long pedunculate panicle of numerous cincinni; basal cincinnus with a leaflike involucral bract at base, with bisexual flowers, others without involucral bracts, with only male flowers. Flowers actinomorphic. Sepals free, boat-shaped, herbaceous, galeate at apex. Petals free, purple or white, broadly linear or oblanceolate. Stamens 6, all fertile, equal; filaments lanate; anther locules parallel, ellipsoid, longitudinally dehiscent. Ovary 3-loculed; ovules 8 per locule. Capsule 3-valved, ovoid, trigonous; seeds 4--8 per valve, polygonal, reticulate; hilum linear.