Herbs annual, hairy or glabrous. Branches terete or 3-angled, stout. Leaves alternate, terete or semiterete, fleshy, apex obtuse or easily deciduous spinose mucronate. Flowers solitary in bract axils, bisexual, with 2 bractlets. Perianth segments 4 or 5, lanceolate, membranous, proximally hardened and usually connate into an urceolate tube, without an appendage, hairy or rarely glabrous. Disk entire. Stamens 4 or 5, inserted on disk; filaments filiform, compressed; anthers oblong, base free, apex with a vesicular appendage. Ovary ovoid, laterally compressed; ovule pendulous on long funicle; style slender; stigmas 2. Utricle broadly ovoid to globose; pericarp membranous, free from seed. Seed vertical, globose, laterally compressed; testa slightly fleshy, embryo planospiral; perisperm absent.