168 CYPERACEAE 



umbel, sometimes becoming 6 dm. long: umbel mostly compound, of 3-12 rays varying 

 from 1-20 cm. in length, with 1 or more spikes sessile in the involucre : spikelets numer- 

 ous, ovate, 6-14 mm. long, acutish, many-flowered : scales oblong-ovate, fully 2 mm. long, 

 red-brown, pinched at the ends. 



In sandy soil. North Carolina to Florida, and California, and in Mexico and Central America. 

 Spring to fall. 



26. Cypenis pseudove*getus Steud. Perennial by thickened tuber-like joints of 

 the rootstocks. Leaf-blades 2-6 mm. wide, smooth, nodulose, the midvein prominent : 

 scapes rather stout, 3-13 dm. high, often equalled by the leaves : bracts of the involucre 

 4-6, spreading : umbel several-rayed, compound : spikelets ovate, flat, many-flowered, light 

 green, densely capitate, 4-6 mm. long : scales keeled, conduplicate, 1 -nerved, curved, acute : 

 stigmas 3 : achene linear, 3-angled, slightly stalked. [C. calcaratus Nees.] 



In marshes, Delaware to Kansas, Florida and Texas. Summer and fall. 



27. CypeniB Surinamensis Rottb. Perennial, pale green. Leaves overtopped by 

 the scape ; blades mostly 1.5-4 mm. wide, usually rough along the margins : scapes slen- 

 der, solitary or tufted, 2-12 dm. tall, naked and rough above : bracts of the involucre 

 usually 3-5, one or all longer than the rays of the umbel, rough-margined : umbels mostly 

 compound, of generally 8-12 rays of various lengths, several spikes sessile or clustered in 

 the involucre : spikelets oblong or linear-oblong, 5-12 mm. long, yellow, blunt, 40-50- 

 flowered, sometimes densely clustered: scales ovate, nearly 1.5 mm. long, deciduous in 

 age : achenes 3-angled, oblong, about 0.8 mm. long, brown, pinched at both ends. 



In sandy swamps, Florida to Texas, and throughout tropical America. Spring to fall. 



28. Cyperus reftexus Vahl. Perennial, bright green. Leaves overtopped by the 

 scape ; blades 1-4 mm. broad, smooth : scapes often tufted, slender, 1-7 dm. tall, smooth : 

 bracts of the involucre 3-5, one or more surpassing the umbel, often compound, of 2-5- 

 rays and one or more spikes sessile in the involucre or capitate : spikelets ovate or ovate- 

 lanceolate, 4-6 mm. long, red or reddish brown, 20-25-flowered ; scales ovate, about 1.5 

 mm. long, acute, imbricated : achenes 3-angled, elliptic, barely 1 mm. long, pinched at 

 the base, short-beaked. 



In sandy soil, Texas. Also in tropical America. Spring to fall. 



29. Cyperus Iria L. Annual, bright green. Leaves mostly overtopped by the 

 scape ; blades 2-4 mm. wide, revolute, striate : scapes erect, sometimes tufted, 2-5 dm. 

 tall, smooth : bracts of the involucre usually 5, the longer ones surpassing the umbel, 

 curved : umbel of 5-9 rays of various lengths, compound : spikelets narrowly oblong, 5-10 

 mm. long, yellowish or brownish, numerous, 12-26-flowered, rather lax: scales obovate or 

 nearly orbicular, fully 1 mm. long, thin, mucronulate, deciduous at maturity: achenes 

 sharply 3-angled, oblong-obovoid, about 1 mm. long, reddish, minutely apiculate, slightly 

 surpassing the scales. 



In swamps mostly near the coast and rice fields, North Carolina to Florida and Texas. Naturalized 

 from the tropics. Spring to fall. 



30. Cypenis distans L. Perennial, bright green. Leaves often overtopping the 

 scape; blades 5-12 mm. wide, striate: scapes 3-15 dm. tall, erect, smooth, not jointed: 

 bracts of the involucre 5, the longer ones surpassing the umbel, ascending, spreading : 

 umbels compound, of several slender rays and one or more spikes sessile in the involucre : 

 spikelets numerous, very slender, linear-filiform, 1-2.5 cm. long, chestnut-colored, spicate 

 and rather loosely disposed : scales oblong, fully 2 mm. long, blunt, sharply keeled : achenes 

 3-angled, narrowly oblong-obovoid, 1.5 mm. long, abruptly pointed. 



In swampy grounds or wet woods, North Carolina and Georgia. Widely distributed in the tropics. 

 Spring to fall. 



31 Cyperus cephalanthus Torr, & Hook. Perennial, bright green. Leaves over- 

 topped by the scape ; blades mostly 5-8 mm. wide, rough on the margins and the nerves 

 beneath : scapes erect, 6-15 dm. tall, rough on the angles near the top : bracts of the in- 

 volucre often 4 or 5, several much elongated and surpassing the umbel, drooping in age : 

 umbel of 4-7 rays and one or more spikes sessile in the involucre : spikelets linear or oblong- 

 linear, numerous and densely capitate, 6-10 mm. long, light chestnut-colored, scales oval- 

 elliptic, 3 mm. long, acute, with several sharp ribs along the back, loosely imbricated, 

 deciduous: achenes 3-angled, elliptic or obovoid-elliptic, barely 1.5 mm. long, rather ab- 

 ruptly pointed. 



In low grounds, Louisiana and Texas. Spring to fall. 



32. Cyperus Haspan L. Perennial by short rootstocks. Leaves reduced to mem- 

 branous acuminate sheaths : scapes weak, tufted, 3-10 dm. high : bracts of the involucre 

 about 2, usually less than 2 mm. wide : umbel simple or compound, the longer rays 2-5 

 cm. long : spikelets few, capitate, linear, acute, many-flowered, 6-12 mm. long, about 1 

 mm. wide : scales oblong or oblong-lanceolate, reddish brown, acute, mucronulate, keeled, 



