Chenop. Monogr. Enum., 111. 1840.
Shrubs, glabrous. Stems apparently jointed and fleshy when young, becoming woody and not jointed, not armed; some stems terminated by an inflorescence, others entirely vegetative. Leaves opposite, united at base, decurrent forming fleshy joints (sterile segments)on stem, eventually deciduous; blades fleshy triangular projections at tip of joints, edges with narrow scarious margins. Inflorescences terminal and lateral, spikelike, apparently jointed, each joint (fertile segment) consisting of 2 opposite, axillary 3(–5)-flowered cymes embedded in and adnate to fleshy tissue of distal internode; flowers in each cyme arranged in transverse row, central flowers separating lateral flowers, slightly larger, flowers in each cyme partially separated by flaps of tissue which persist on stem when flowers have fallen. Flowers bisexual or unisexual, more or less radially symmetrical; perianth segments persistent in fruit, 3–4, united except at tip, fleshy; stamens 1–2; styles 2–3. Fruits: utriclelike, ellipsoid; pericarp membranous. Seeds vertical, ellipsoid; seed coat light brown, membranous, pubescent; hairs strongly curved or hooked and slender, or conic, straight or slightly curved; perisperm absent. x = 9.
w North America, warm temperate and tropical coasts of Eurasia, Africa.
Species up to 6 (1 in the flora).