Herbs perennial, 20-120 cm tall. Stem quadrangular, pubescent; nodes slightly inflated; branches opposite. Petiole 0.5-1.5 cm, somewhat hairy; leaf blade broadly obovate or elliptic-oblong, 1.5-7 × 0.4-4 mm, papery, both surfaces hairy, base cuneate or rounded, margin entire or undulate, apex obtuse, with a mucro. Spikes terminal, erect, reflexed after anthesis, 10-30 cm; rachis angular, stout, densely hairy. Bracts lanceolate, 3-4 mm, apex acuminate; bracteoles spiny, shiny, 2.5-4.5 mm, rigid, base 2-winged; wings 1.5-2 mm, membranous, margin entire. Tepals lanceolate, 3.5-5 mm, with a vein. Stamens 2.5-3.5 mm; pseudostaminodes truncate or crenate at apex, fimbriate and ciliate. Utricles ovoid, 2.5-3 mm. Seeds brown, ovoid, ca. 2 mm. Fl. Jun-Aug, fr. Oct. 2n = 42, 48, 84, 96.