22. SCHOENUS Linnaeus, Sp. Pl. 1: 42. 1753; Gen. Pl. ed. 5, 26. 1754.
Blackhead sedge [Greek schoinos, rushlike plant]
Gordon C. Tucker
Herbs, perennial, cespitose, rhizomatous. Culms distally branched, terete. Leaves basal; ligules absent; blades involute or subcylindric. Inflorescences terminal, sometimes pseudolateral, capitate [diffusely branched]; spikelets (1–)10–25, black or very dark purple; involucral bracts 1–2, spreading or erect, leaflike. Spikelets: scales 3–8, distichous, black or very dark purple, 2–3 proximal scales empty, distal scales each subtending flower. Flowers bisexual; perianth bristles 0–6, shorter or longer than achene, smooth or scabrous; stamens 3; styles deciduous, linear, 3-fid. Achenes rounded-trigonous to subterete.
Species ca. 80 (1 in the flora): worldwide in warm-temperate and tropical regions.
Schoenus is restricted mostly to Australasia; a few species occur in Africa, Eurasia, and the New World.
SELECTED REFERENCE
Kükenthal, G. 1938. Vorarbeiten zu einer Monographie der Rhynchosporoideae. Schoenus. Repert. Spec. Nov. Regni Veg. 44: 1–32, 162–195.
