Herbs annual, ephemeral, appressed sericeous-villous, rarely glabrous. Stem much branched, terete. Leaves sessile, linear, terete or semiterete, apex acute or acuminate. Flowers axillary, solitary, bisexual, with 2 navicular, embracing bractlets. Perianth segments 2, 3, or 5, narrowly ovate-lanceolate to elliptic, slightly enlarged in fruit, membranous or papery, proximally becoming leathery and adaxially concave, without an appendage, veinless, glabrous or abaxially slightly hairy near apex. Stamens 1-5, inserted on an obscure disk; filaments compressed; anthers oblong or sagittate, exserted from perianth; connective protruding, becoming a thickened, solid appendage. Ovary broadly ovoid, compressed; ovule subsessile; style cylindric; stigmas 2, filiform. Utricle enclosed in perianth, ovate or broadly oblong; pericarp membranous or thinly papery, slightly fleshy distally, glabrous, not adnate to seed. Seed vertical, globose or subglobose, compressed; testa membranous; embryo planospiral; perisperm absent.

Between 11 and 15 species; C and SW Asia, SE Europe; four species in China.