Eleocharis geniculata (L.) Roem. & Schult.
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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 - Densely tufted annual, 10-60 cm tall; roots filiform; culms obscurely angled, 0.4-0.9 mm wide, prominently ribbed, smooth, green, glabrous. Sheaths finely many-veined, smooth, green, glabrous, reddish to purplish at base, eligulate, closed at summit, with a concave to truncate orifice, the back prolonged into a short, acuminate, cuspidate tip. Inflorescence a single, erect spikelet at the summit of the culm; spikelets ovate, 2.5-4 x 2-3 mm , with obtuse apex, many-flowered, the flowers spirally imbricate; scales boat-shaped, obtuse at apex, glabrous, the basal scales elliptic to widely elliptic, the lowest one usually empty, 1.2-1.5 X 1.0- 1.5 mm , 1-nerved, light green to straw-colored, smooth and shiny, with pale green midrib thickening toward the apex, tipped by an expanded callosity, the upper scales elliptic, 1.5-2 x 1-1.3 mm , dark green to brown with pale margins. Stamens 3, the anthers 0.5-0.6 mm long; styles 2-branched, the branches fimbriate-scaly, the short, unbranched portion smooth. Achene 2-sided, obovate, 1-1.1 (including style base) x 0.6-0.8 mm , smooth, lustrous, dark purplish black to black; bristles 6-8, rarely absent, whitish to tawny, retrorsely barbed, equaling or exceeding the whitish, depressed-conic, saucer-shaped tubercle.
Distribution and Ecology - Common in sandy, waterlogged areas. Concordia (A4253), Battery Gut (A4171), Fish Bay Gut (A2497). Also on St. Croix, St. Thomas, and Tortola; a pantropical weed.
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Discussion
Scirpus caribaeus Rottb., Descr. Icon. Rar. P L 24. 1773. Eleocharis caribaea (Rottb.) S.F. Blake, Rhodora 20: 24. 1918.
Scirpus geniculatus var. minor Vahl, E n u m . P L Syst. 2: 251. 1806. Eleocharis geniculata var. minor (Vahl) R o e m . & Schult., Syst. Veg. 2: 150. 1817. Eleocharis capitata R. Br., Prodr. 255. 1810.