186 CYPERACEAE 



32. Eleocharis tricost^ta Torr. Perennial by short rootstocks. vScapes very slender, 

 erect, compressed, striate, 3-6 dm. tall : upper sheath obliquely truncate, toothed on one 

 side: spikelet oblong, becoming oblong-cylindric, obtuse, many-flowered, 10-18 ram. long, 

 2-3 mm. in diameter : scales ovate, thin, deciduous, obtuse, brown with green midveinsand 

 scarious margins : perianth-bristles none : stigmas 3: achenes obovoid, 0.8-1 mm. long, 

 3-angled, brown, dull, papillose, with the three angles strongly ribbed ; tubercle conic, 

 acute, light brown, constricted at the base, minute, very much shorter than the achene. 



In wet soil, southern New York to Florida. Summer and fall. 



33. Eleocharis tenuis (Willd. ) Schult. Perennial by rootstocks. Scapes tufted, 

 filiform, mostly erect, 4-angled with concave sides, 2-4 dm. tall : upper sheath obliquely 

 truncate, toothed an one side : spikelet narrowly oblong, mostly acute, many-flowered, 

 thicker than the scape, 6-10 mm. long, about 2 mm. in diameter : involucral bract 1 : 

 scales thin, obovate or ovate-oblong, obtuse, the midvein greenish, the margins scarious : 

 perianth-bristles 2-4, shorter than the achene, fugacious or wanting : stigmas 3 : achenes 

 obovoid, about 1 mm. long, obtusely 3-angled, yellow to brown, irregularly ridged-reticu- 

 lated or papillose, more or less persistent on the rachis of the spikelet after the scales have 

 fallen ; tubercle conic, short, acute. 



In wet soil, Cape Breton Island to Ontario, Manitoba, Florida and Texas. Spring and summer. 



34. Eleocharis arenicola Torr. Perennial by horizontal rootstocks. Scapes very 

 slender, tufted, 1.5-4-5 dm. tall, grooved, mostly erect : spikelets oblong to ovoid-oblong, 

 4-12 mm. long, 2.5-3.5 mm. thick, many-flowered : scales oblong or ovate, thin, blunt, 

 each with a brown apex and whitish margins : perianth-bristles 6, persistent, the longer as 

 long as the achene : achenes 3-angled, about 1 mm. long, oblong-obovoid or obovoid, faintly 

 reticulated ; tubercle thick, deltoid. 



On sandy shores and in swamps, South Carolina to Florida and Texas. Spring to fall. 



35. Eleocharis acuminata ( Muhl. ) Nees. Perennial by stout rootstocks, similar to 

 the next preceding species but stouter. Scapes flattened, striate, slender but rather stiff, 

 tufted, 2-5 dm. tall : upper sheath truncate, sometimes slightly 1 -toothed : spikelet ovoid 

 or oblong, obtuse, thicker than the scape, many-flowered, 6-12 nmi. long : scales oblong or 

 ovate-lanceolate, acute, purple-brown with greenish raidveins and hyaline white margins, 

 deciduous : perianth-bristles 1-5, shorter than or equalling the achene, fugacious, or want- 

 ing : stigmas 3, exserted : achenes obovoid, 1.5 mm. long, obtusely 3-angled, light yel- 

 lowish brown, papillose, much longer than the depressed conic acute tubercle, persistent 

 on the rachis as in E. tenui.t. 



In wet soil, Anticosti to Manitoba, Georgia, Louisiana and Nebraska. Summer. 



36. Eleocharis cylindrica Buckl. Perennial by slender rootstocks. Scapes very 

 slender, tufted : spikelets linear-cylindric, or slightly flattened, 1-2 cm. long, about 3 mm. 

 thick, acutish, many-flowered : scales various, the lower ovate and blunt, the upper ovate 

 or oblong-lanceolate and acute, with whitish hyaline margins : perianth-bristles wanting : 

 achenes obovoid, fully 0.5 mm. long, yellowish, constricted at the ends but especially under 

 the acute tubercle. 



In sandy soil, Texas. Summer and fall. 



37. Eleocharis rostellkta Torr. Perennial by a short caudex. Scapes slender, wiry, 

 the fertile ones erect or ascending, the sterile reclining and rooting at the summit, grooved, 

 3-15 dm. long : upper sheath truncate : spikelet oblong, narrowed at both ends, thicker 

 than the scape, 10-20-flowered, 6-12 mm. long, about 2 mm. in diameter : scales ovate, 

 obtuse or the upper acute, green with somewhat darker midveins : perianth-bristles 4-8, 

 retrorsely barbed, longer than the achene and tubercle : stigmas 3 : achenes oblong-ob- 

 ovoid, 1.5 mm. long, obtusely 3-angled, their surface finely reticulated ; tubercle conic- 

 subulate, about 5 as long as the achene or shorter, capping its summit, partly or entirely 

 falling away at maturitv. 



In marshes and wet meadows, New Hampshire to Vermont and western New York, British Colum- 

 bia, Florida, Texas, Mexico and California. Also in Cuba. Summer and fall. 



11. FIMBRISTYLIS Vahl. 



Annual or perennial scapose herbs. Spikelets umbellate or capitate, terete, several to 

 many-flowered, subtended by a 1-many-leaved involucre, their scales spirally imbricated 

 all around, mostly deciduous, all fertile. Perianth none. Stamens 1-^3. Style pubescent 

 or glabrous, its base usually much enlarged, but falling away from the summit of the 

 achene at maturity. Stigmas 2-3. Achenes lenticular, biconvex, or 3-angled, reticulated, 

 cancellate, or longitudinally ribbed or striate. Tlie plants flower mainly in summer and fall. 



