Cyperus rotundus L.
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Authority
Acevedo-Rodríguez, Pedro & collaborators. 1996. Flora of St. John, U.S. Virgin Islands. Mem. New York Bot. Gard. 78: 1-581.
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Family
Cyperaceae
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Scientific Name
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Description
Species Description - Stoloniferous perennial, 10-80 cm tall; stolons elongate, bearing tubers; culms solitary, tuberous at base, 3-angled to subcompressed, 1-3 mm wide, finely ribbed, smooth, glabrous, sheathing base of culm 3-10 mm wide. Leaves 7-17, clustered at base; blades flattish, 5-40 cm long, 2-6(-8) mm wide, finely veined, glabrous, scabrous along margins and midvein beneath toward apex, acuminate at apex; sheaths short, finely veined, septate, glabrous, pale brown, faintly short-ligulate on lower sheaths, eligulate on upper sheaths. Inflorescence a simple to compound umbel-like corymb, 3-17 x 2.5-21 cm; involucral bracts 2-5, leaflike, to 20 cm long, 1.3-6 mm wide, scabrous along margins and midvein beneath toward the acuminate apex; rays 3-7, unequal, 4-10 cm long, 0.5-1.1 mm wide, finely ribbed, obscurely 3-angled to subcompressed; spikes broadly ovate, 1.5-4 x 1.5- 7 cm; spikelets 2-12, linear-lanceolate, compressed, 10-45 x 2 mm, acute at apex; rachilla flexuous, broadly winged, bearing 11- 51 flowers, persistent; scales deciduous, ovate to ovate-elliptic, 3-3.5 x 2-2.4 mm , subacutely keeled, 9-nerved (marginal ones inconspicuous) membranous, reddish brown to purplish brown, with scarious margins, the apex obtuse. Stamens 3, the anthers linear, 1.7-2.2 mm long, apiculate; styles elongate, subulate, 3-branched to below the middle, the unbranched portion subflattened.
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Discussion
Common name: nut-grass.
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Distribution
Occasional in sandy soils, along beaches, roadsides, and disturbed habitats. Coral Bay (Raunkicer s.n.). Also on St. Croix, St. Thomas, and Virgin Gorda; a cosmopolitan weed.
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