254 CYPERACEAE. 



16. Eleocharis melanocarpa Torr. Black-fruited Spike-rush. (Fig. 592.) 



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



Perennial by short rootstocks, culms flattened, striate, 

 tufted, slender, erect, wiry, IC/-2C/ tall. Upper sheath 

 truncate, i -toothed; spikelet oblong or cylindric-oblong, 

 obtuse, 3 // -6 // long, iX // - 2// in diameter, many-flow- 

 ered, thicker than the culm; scales ovate, obtuse, brown, 

 with a lighter midvein and scarious margins; 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, obpyramidal, 

 black, smooth, its superficial cells nearly quadrate; tu- 

 bercle 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. 



17. Eleocharis albida Torr. White Spike-rush. (Fig. 593.) 



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 // -4 // long, ij^ // -2 // in 

 diameter, many-flowered, thicker than the culm; 

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

 obtuse, deciduous; bristles about 6, downwardly 

 barbed, persistent, 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 

 Mexico, near the coast. June-Aug. 



18. Eleocharis tricostata Torr. Three-ribbed Spike-rush. (Fig. 594. ) 



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 ob- 

 long, becoming oblong-cylindric, obtuse, many-flow- 

 ered, 5 // -9 // long, \"-\%" in diameter; scales ovate, 

 thin, deciduous, obtuse, brown with a green midvein 

 and scarious margins; bristles none; stamens 3; style 

 3-cleft; achene obovoid, 3-angled, brown, dull, papil- 

 lose, 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, southern New York to Florida. July-Sept. 



