1. Schoenus nigricans  Linnaeus, Sp. Pl.  1: 43.  1753.  
Black sedge  
Rhizomes short, oblique.  Culms hollow, glabrous.  Leaves: basal sheaths blackish, conspicuously wider than leaf blades; blades 10–40 cm × 0.8–2 mm, margins involute, smooth or scabridulous.  Inflorescences loosely ovoid, 1–2 cm; bracts 1 or 2, oblique to erect, green to dark brown or black, 1–6 cm × 1–1.5 mm.  Spikelets (1–)10–25, flattened, oblong-ellipsoid; rachilla wingless, ± deciduous at maturity; basal scales 2–3, sterile; floral scales 3–8, laterally veinless, medially 1-veined, oblong, apex acute, not mucronate, distally scabrellate.  Flowers: perianth bristles 0–6, smooth or scabrellate; anthers linear, connective apices subulate, conspicuous; styles 0.6–1 mm; stigmas 0.5 mm.  Achenes whitish, ovoid to ellipsoid, 1–1.5 × 0.9–1.2 mm, glossy, apex obtuse, smooth or barely reticulate.  2n = 54, 55.
Fruiting summer.  Damp, calcareous or alkaline grasslands; 0–2000 m; Calif., Fla., Nev., Tex.; Mexico; Eurasia; Africa; Australia.