Herbs annual, erect or ascending, 10-50 cm tall. Stem branched from or near base, glabrous or obscurely pubescent. Petiole 2-10 mm; leaf blade obovate, oblong, or linear, 1.5-6.5 mm × 0.3-2.5 cm, both surfaces glabrous or adaxially pubescent, base attenuate, apex acute or obtuse, with a mucro. Heads globose, becoming somewhat lengthened, with 3-7-flowered cymes; rachis 0.2-3.5 cm, glabrous or pubescent. Bracts and bracteoles ovate-lanceolate, 3-5 mm, white on margin and with green or purple (?red) midvein, apex long acuminate. Tepals obliquely spreading at anthesis, later erect, ovate-lanceolate or oblong-lanceolate, 4-5 mm. Stamens 5; filaments connate at base. Ovary ovoid, glabrous; style nearly as long as filaments. Utricles enclosed in persistent perianth, pale green, ovoid, 3-3.5 mm in diam., dehiscent by lid. Seeds 1.5-2 mm in diam. Fl. May-Jun, fr. Jul-Aug. 2n = 32.