Herbs annual, subshrubs, or shrubs, sometimes glaucous, glabrous, rarely pubescent. Stem erect, obliquely spreading, or prostrate. Leaves usually sessile and linear, terete or semiterete, rarely clavate or slightly compressed, fleshy, margin entire. Flowers small, bisexual, sometimes also female, usually 3 to numerous in glomerules, these axillary or on dwarf, axillary branchlets, sometimes dwarf branchlet base fused to leaf base and glomerule thus appearing to arise from petiole; bractlets 2 per flower, white, scale-like, membranous. Perianth subglobose, hemispheric, or urceolate, 5-parted or -lobed, slightly fleshy or herbaceous; segments abaxially thickened or becoming winglike or hornlike, rarely not modified, adaxially concave or cucullate. Stamens 5; filaments short, flattened; anthers cylindric, ellipsoid, or subglobose, without an appendage. Ovary ovoid or globose; stigmas 2 or 3(-5), usually recurved, papillate throughout. Utricle enclosed by perianth; pericarp membranous, free from seed. Seed horizontal or vertical, lenticular, reniform, ovoid, or globose; testa thinly leathery or membranous; embryo green or whitish, planospiral, slender; perisperm scant or absent.

About 100 species: Asia, Europe, North America, and seashores worldwide: 20 species (two endemic) in China.