Description from Flora of China
Subshrubs or shrubs, glabrous or with papillate processes. Annual branches terete or obtusely 4-angled, jointed, slightly fleshy. Leaves opposite, sessile, linear, semiterete or clavate, fleshy, rarely subulate or scale-like, base slightly expanded, apex obtuse or with a short, acicular awn; leaf axil usually cottony. Flowers solitary in leaf axils, bisexual, with 2 bractlets. Perianth subglobose; segments 5, orbicular to broadly elliptic, herbaceous, abaxially somewhat thickened, bearing a transverse, winglike process a little below apex in fruit, adaxially convex, margin membranous, apex usually recurved. Disk cupular or discoid, usually with 5 interstaminal lobes. Stamens 5, inserted on disk; filaments subulate, compressed; anthers broadly ovate-cordate, apex without an appendage or mucronate. Style very short, apex slightly contracted; stigmas 2-5-lobed. Utricle enclosed in perianth, hemispheric, apex truncate or somewhat convex; pericarp fleshy. Seed horizontal; embryo spiral; perisperm absent.
About 20 species: C Asia; three species in China.