Herbs annual, 15-40 cm tall. Stem erect; branches opposite, obliquely spreading, green or reddish, hispid; internodes 0.5-1.5 cm, ribbed. Leaves 5-10 mm, margin membranous, apex subulate, with an acicular awn; leaf axil hispid. Bractlets navicular, slightly shorter than perianth, apex pungent. Perianth segments oblong-lanceolate, membranous, slightly enlarged and becoming papery in fruit; outer 3 segments abaxially winged; wing erect on upper segment, usually recurved on lower segments, ovate to broadly so, finely veined. Anthers minute, apex with a mucronate appendage. Utricle ovoid or cylindric-ovoid, compressed, 2-2.5 mm. Pericarp yellow-brown, glabrous, not adnate to seed. Testa yellow-brown; embryo green, planospiral. Fl. and fr. Jul-Oct.