Annual or perennial herbs, sometimes twining. Leaves alternate, petiolate, ovate, deltoid or sagittate; ochreas tubular, truncate, brownish, membranous, soon disintegrating. Flowers bisexual (sometimes functionally unisexual), in lax spike-like or branched panicles; perianth segments 5(–6), the outer 3 larger, usually sepaloid, green or whitish, enlarging in fruit and prominently keeled or winged; stamens 8; style 3-branched, stigmas capitate to peltately attached. Nut trigonous or triquetrous, remaining enclosed within perianth.
About 12 species from temperate Northern Hemisphere countries; 3 species naturalised in Australia.