Annuals, dwarf shrubs, rarely dwarf trees. Glabrous, papillose or with fugacious hairs. Young stems pale green or purplish throughout, or with longitudinal green lines, densely leafy. Leaves alternate, entire, sessile or shortly petiolate, linear to almost circular, ±succulent, terete, semi-terete or flat on both sides; isolateral, with C3 or C4 anatomy and all bundles arranged in one plane. Inflorescences terminal, spike-like, usually branched. Bracts leaf-like, but successively shorter. Bracteoles membranous, ovate, with entire or eroso-dentate margins. Flowers sessile, in cymose axillary clusters of (1)3-many, or the clusters located on the petiole at some distance from the leaf axil, more rarely on short ebracteate axillary branches; usually the first ones bisexual and protandrous, the lateral pistillate with rudimentary stamens, rarely the first ones staminate with pistil rudiment. Tepals 5, fused for 1/5-3/5, green, the free lobes incurved, often succulent, with membranous margins and cucullate apex, persistent, after anthesis usually enlarged, dorsally sometimes with bulge-, horn- or wing-like outgrowths or becoming spongy throughout. Stamens 5, rarely less by abortion; antitepalous, unappendaged; filaments band-shaped, inserted on an epitepalous rim or individually in lower part of tepals, finally surpassing the tepals. Ovary superior, very rarely semi-inferior, conical, ovoid, obpyriform or cylindric, with truncate or acutish apex; style absent; stigmas 2 or 3, rarely more, usually subulate, papillose throughout, spreading or flexuose, in pistillate flowers usually much longer. Fruit horizontal, vertical or oblique, with thin, papery pericarp. Seeds slightly to strongly flattened, disc-shaped to almost globular, often drop-shaped, beaked; testa usually crustaceous, black or chestnut-coloured, smooth and glossy or ±sculptured by domed to papillose epidermal cells and then dull to moderately shining; embryo flat spiral; endosperm scanty or absent; in case of heterocarpy a second type of seeds present that are larger in diameter, more strongly flattened, with very thin, light brown testa and the twisted embryo clearly visible from the outside.