GENUS 3. 



SEDGE FAMILY. 



3'7 



19. Eleocharis melanocarpa Torr. Black-fruited Spike-rush. Fig. 776. 



Eleocharis melanocarpa Torr. Ann. Lye. N. Y. 3 : 311. 1836. 



Perennial by short rootstocks, culms flattened, striate, 

 tufted, slender, erect, wiry, io'-2o' tall, sometimes prolif- 

 erous. Upper sheath truncate, i-toothed; spikelet oblong 

 or cylindric-oblong, obtuse, 3"-6" long, \\"-2" in diam- 

 eter, many-flowered, thicker than the culm ; scales ovate, 

 obtuse, brown, with a lighter midvein and scarious mar- 

 gins ; bristles 3-4, fragile, downwardly hispid, equalling or 

 longer than the achene, fugacious or perhaps sometimes 

 wanting; stamens 3; style 3-cleft; achene 3-angled, ob- 

 pyramidal, black, smooth, its superficial cells nearly quad- 

 rate ; tubercle depressed, covering the summit of the 

 achene, light brown, pointed in the middle. 



In wet sandy soil, eastern Massachusetts and Rhode Island 

 to Florida, near the coast. Also in northern Indiana. July- 

 Sept. 



20. Eleocharis albida Torr. White Spike-rush. Fig. 777. 



Eleocharis albida Torr. Ann. Lye. N. Y. 3 : 304. 1836. 



Annual, roots- fibrous, culms very slender, tufted, 

 nearly terete, striate, erect, 4'-8' tall. Upper sheath 

 very oblique and toothed on one side ; spikelet ovoid- 

 globose or oblong, obtuse, 2"-^' long, iJ"-2" in di- 

 ameter, many-flowered, thicker than the culm; scales 

 pale green or nearly white, rather firm, ovate, obtuse, 

 deciduous; bristles about 6, downwardly barbed, per- 

 sistent, as long as the achene ; stamens 3 ; style 3-cleft ; 

 achene broadly obovoid, nearly black when ripe, 

 3-angled, smooth; tubercle ovoid-conic, contracted or 

 truncate at the base, about one- fourth as long as the 

 achene. 



In wet soil, Maryland to Florida, Texas and eastern Mex- 

 ico, near the coast. Recorded from Jamaica. June-Aug. 



21. Eleocharis tricostata Torr. Three-ribbed Spike-rush. Fig. 778. 



Eleocharis tricostata Torr. Ann. Lye. N. Y. 3 : 310. 1836. 



Perennial by short rootstocks, culms very slender, 

 erect, compressed, striate, i-2 tall. Upper sheath 

 obliquely truncate, toothed on one side; spikelet oblong, 

 becoming oblong-cylindric, obtuse, many-flowered, 5"-9" 

 long, i "-14" in diameter; scales ovate, thin, deciduous, 

 obtuse, brow : n with a green midvein and scarious mar- 

 gins; bristles none; stamens 3; style 3-cleft; achene 

 obovoid, 3-angled, brown, dull, papillose, strongly ribbed 

 on each of its angles ; tubercle conic, acute, light brown, 

 constricted at the base, minute, very much shorter than 

 the achene. 



In wet soil, eastern Massachusetts to southern New York 

 and Florida. July-Sept. 



