Annual, polygamous-monoecious herbs. Leaves alternate, entire or nearly so, generally ovate; ochreae membranous, truncate and cleft at apex. Flowers clustered at nodes or arranged in axillary, leafless, interrupted racemes; flowers of lower whorls pistillate, those or upper ones hermaphrodite or staminate; a few flowers at base of stem are into the soil by contractile roots and ripen under ground. Staminate flowers pedicellate; perianth herbaceous, 3-6-partite with equal, spreading segments. Pistillate flowers more or less sessille; perianth herbaceous, urceolate, 6-lobed. Stamens 4-6. Ovary trigonous, 1-ovuled; styles 3, short, with fringed stigmas. Fruiting perianth much accrescent, indurated, with a trigonous tube pitted between ribs, outer 3 segments spinescent, spreading or recurved at apex, inner ones erect, connivent. Achene free, triquetrous, with membranous-leathery pericarp. Embryo lateral or peripheral; cotyledons narrowly linear to club-shaped.