Herbs or woody plants, sometimes climbers, rarely trees. Stems usually jointed, with swollen nodes. Leaves mostly alternate, rarely opposite or whorled, simple, entire or variously lobed or toothed; stipules commonly connate into a sheath (ochrea). Inflorescences - panicles, spikes or heads, composed of cymose clusters or sometimes of single flowers. Bracts 1-2, connate into a sheath (ochreole). Pedicels usually articulate. Flowers hermaphrodite or sometimes unisexual (then plants monoecious or dioecious), actinomorphic. Perianth 2-whorled, sepaloid or coloured, usually persistent, of 3-6 free or connate tepals, the inner whorl sometimes accrescent or modified in fruit. Stamens 6-9, rarely more or less, opposite tepals, with 2-celled anthers. Ovary superior, 1-celled and 1-ovuled; styles 2-4, free or connate at base. Fruit a flat or angular or winged achene, often enclosed within the membranous or leathery perianth. Endosperm copious, mealy; embryo eccentric or lateral, curved or straight.