CYPERACEAE 173 



finely ribbed, closely imbricated : achenes 3-angled, oblong-prismatic, nearly 2 mm. long, 

 abruptly pointed. 



In sand, Florida to Texas. Spring to fall. 



60. Cyperus Lancastri6nsis Porter. Perennial by ovoid or oblong corms. Leaf- 

 blades 4-6 mm. wide : scapes slender, smooth, mostly longer than the leaves, 3-8 dm. tall : 

 bracts of the involucre 4-7, the longer much exceeding the inflorescence : umbel simple, 

 5-9-rayed, the longer rays 5-10 cm. long, their sheaths nearly truncate : spikes oval, ob- 

 tuse, 1-2.5 cm. long : spikelets densely clustered, 8-10 mm. long, linear, nearly terete, 

 2-4-flowered, the lower reflexed, the middle ones spreading, all separating from the axis at 

 maturity : scales green, strongly several-nerved, the flowering ones lanceolate, subacute : 

 stigmas 3 : achenes linear, obtuse, 2.5-3 mm. long, apiculate, 2-3 times as long as thick, f 

 as long as the scale. 



In dry fields, New Jersey and Pennsylvania to Virginia and Alabama. Summer and fall. 



61. Cyperus uniflorus Torr. & Hook. Perennial, bright green. Leaves overtopped 

 by the scape ; blades 2-4 mm. wide, smooth : scapes often tufted, slender, 1-7 dm. tall, 

 smooth : bracts of the involucre 4-7, the longer ones surpassing the umbel : umbel simple, 

 of 3-6 slender rays and one or more spikes sessile in the involucre : spikes oval or ovoid, 

 1.5-2 cm. long : spikelets spreading in all directions, usually curved, subulate, 8-12 mm. 

 long, gray-green, attenuate, never densely crowded : scales various, narrow, lower merely 

 acute, upper more or less awn-tipped, closely imbricated : achenes 3-angled, 'oblong or 

 slightly broadest above the middle, 2.5 mm. long, brown. 



In sandy swamps or low grounds, Arkansas and the Indian Territory to Texas, New Mexico and 

 Mexico. Spring to fall. 



62. Cyperus subuniflorus Britton. Similar to the next preceding species in habit, 

 but more slender and smaller throughout. Umbels with fewer rays : spikes globular or 

 ovoid-globose, 6-10 mm. long : spikelets more or less spreading, 3-5 mm. long, without 

 conspicuous subulate tips, little if at all curved : achenes 3-angled, oblong, about 2 mm. 

 long, abruptly pointed. 



In dry soil, the Indian Territory, Texas and Mexico. Spring to fall. 



63. Cyperus tetragonus Ell. Perennial, bright green. Leaves mostly overtopped 

 by the scape ; blades 4-10 mm. broad, smooth or nearly so : scape often solitary, erect, 3-8 

 dm. tall, smooth : bracts of the involucre 8-10, the longer ones surpassing the umbel, as- 

 cending, spreading : umbel mostly compound, of 6-12 slender erect or ascending rays and 

 one or more spikes sessile in the involucre : spikelets linear-oblong, plump, 4-6 mm. long, 

 acute, chestnut-colored, 4-6-flowered, spreading or the lower reflexed : scales oblong, fully 

 3 mm. long, 9-11 -nerved, closely imbricated : achenes oblong or elliptic, 3-angled, 2 mm. 

 long, chestnut-colored, dull. 



In sandy soil, near the coast, North Carolina to Florida and Texas. Spring to fall. 



64. Cyperus flavus ( Vahl ) Nees. Perennial, bright green. Leaves overtopped by 

 the scape ; blades 2-6 mm. wide, smooth : scapes often tufted, 1-6 dm. tall, smooth : bracts 

 of the involucre mostly 4-6, the longer ones surpassing the umbel : umbel capitate, of 3-6 

 sessile cylindric spikes, 1-2 cm. long, or occasionally with 2-3 short rays : spikelets 

 densely crowded, 3-5 mm. long, spreading, chestnut-colored : scales ovate to oblong, 2-2.5 

 mm. long, finely ribbed, often eroded at the apex, closely imbricated : achenes 3-angled, 

 broadly elliptic to obovoid-elliptic, about 2 mm. long, brown, dull. 



In sand, Texas and tropical America. Spring to fall. 



65. Cyperus fuligineus Chapm. Perennial, deep green. Leaves overtopped by the 

 scape ; sheaths blackish ; blades revolute, about as slender as the scape, smooth : scapes 

 tufted, filiform, 1-4 dm. tall, smooth : bracts of the involucre 2, one much shorter than 

 the other : spikelets crowded in a head about 1 cm. in diameter, linear-oblong, 4-7 mm. 

 long, dark brown, 8-12-flowered, often apparently lateral : scales oval or ovate, barely 2 

 mm. long, mucronulate, several-ribbed: achenes 3-angled, oblong-obo void, barely 1.5 mm. 

 long, dark brown, dull. 



In sand, Key West, Florida. Spring to winter. 



66. Cyperus filiculmis Vahl. Perennial by hard oblong corms. Leaf -blades 2-4 mm. 

 wide, keeled : scape smooth, slender, or almost filiform, ascending or reclined, 1.5-4.5 dm. 

 long, usually longer than the rough-margined leaves : spikelets densely clustered in 1-7 

 globose heads, linear, acute, 5-11-flowered, subterete or compressed, 5-12 mm. long, 2 mm. 

 wide or less : scales ovate, acute or obtuse, pale green, strongly 7-11 -nerved, appressed : 

 stigmas 3 : achenes oblong or obovoid, fully 2 mm. long, 3-angled, obtuse, apiculate, dull 

 gray, f as long as the scale, about twice as long as thick. 



In dry fields and on hills, New Hampshire to Ontario, Minnesota, Nebraska, Florida, Kansas, 

 Texas and northern Mexico. Spring and summer. 



