Subshrubs. Woody stem much branched, or reduced to an enlarged, tuberculate caudex; annual branches green, jointed, glabrous or with papillate processes. Leaves opposite, semiterete and fleshy, subulate, scale-like, or obscure, bases united, apex obtuse or acute, sometimes with an acicular awn; leaf axil usually cottony. Flowers solitary in leaf axils, rarely clustered, bisexual; bractlets 2, navicular, usually shorter than perianth. Perianth segments 5, membranous; outer 3 segments broadly elliptic or suborbicular; inner 2 segments ovate; outer 3 or all 5 segments with a winglike appendage abaxially, rarely without such an appendage. Disk cupular, 5-lobed; lobes interstaminal, semiorbicular or linear, adaxially ± granulose glandular. Stamens 5, inserted on disk; filaments subulate, slightly compressed; anthers oblong-ovate, apex obtuse or mucronate. Ovary ovoid, glabrous or papillate; style short; stigmas 2, erect or recurved. Utricle subglobose to broadly ellipsoid, compressed; pericarp fleshy. Seed vertical; embryo spiral; perisperm absent.

About 30 species: from the Mediterranean region to China, Mongolia, and Russia (Siberia); eight species in China.