Annual or perennial herbs or shrubs, often fleshy, glabrous, papillate or hairy. Leaves opposite or alternate, exstipulate, sometimes seemingly wanting, stalked or sessile, entire, dentate-serrate-lobed or irregularly gashed. Flowers solitary, 2—3-nate or glomerate, usually sessile, either axillary or in terminal or axillary dense or interrupted spikes or panicles, ♀ or unisexual, monochlamydous, rarely achlamydous, small; bracts present or absent, usually small, rarely leafy. Perianth herbaceous or sometimes scarious, rarely (in ♀) absent, 3—5-partite with (in bud) imbricate segments, or sometimes almost entirely gamophyllous and then shortly lacerate-dentate or unilaterally cleft, persistent, after anthesis accrescent or not. Stamens often the same number as tepals and opposite to them, sometimes fewer, usually inserted on or near base of perianth; filaments free or shortly connate; anthers dorsifixed or inserted in a basal cleft, 2-celled (4-locellate); cells bursting longitudinally. Ovary free or at the base adnate to the perianth, 1-celled; ovule 1, basal, sessile and erect or suspended from a funicle; styles or stigmas 2-5, linear. Utricle either enclosed by the perianth or not, indehiscent or rarely operculate; seed erect, oblique or horizontal, usually compressed; endosperm mostly present, peripheral, surrounding the embryo; embryo annular or spirally twisted. Distr. Species numerous, inhabitants of the temperate and tropical zones of both hemispheres.