Annual or perennial herbs, rarely shrubs. Stems erect to prostrate, sometimes climbing. Leaves alternate, simple; stipules membranous, forming clasping ochreae, often lacerate, fringed or ciliate. Inflorescences spike-like, glomerate or paniculate. Flowers usually small, hermaphrodite, either solitary or in cymose axillary clusters. Bracts partly membranous and united into a sheathing ochreole. Pedicels jointed. Perianth simple, divided into 5 (rarely more or less) subequal segments, usually enclosing fruit. Stamens 8 (rarely fewer), with 2-celled anthers. Ovary superior, 1-ovuled; style 2-3-parted, with capitate stigmas. Achene triquetrous, trigonous or lenticular. Embryo lateral.