Genus 2. 



SEDGE FAMILY 



10. Cyperus Iria L. Yellow Cyperus. 

 Fig. 730. 



Cyperus Iria L. Sp. PI. 45. 1753. 



Annual with fibrous roots; culms tufted, 

 4-20' tall, 3-angled. Basal leaves i"-?,\" 

 wide, shorter than the culm or equalling it, 

 those of the involucre similar, the longer ones 

 surpassing the inflorescence; umbel several- 

 rayed, usually compound; spikelets numerous, 

 spicate, narrowly oblong, 2"-6" long, about 1" 

 wide, flattened, several-many-flowered ; rachis 

 nearly wingless ; scales obovate, yellow to 

 yellow-brown, blunt, mucronate, 3-5-nerved on 

 the back ; stamens 2 or 3 ; achene oblong- 

 obovoid, trigonous, about &" long. 



Cultivated ground, Hempsted, Long Island; 

 swamps. North Carolina to Florida and Texas. 

 Naturalized from Asia. 



11. Cyperus Schweinitzii Torr. Schweinitz's Cyperus. Fig. 731. 



C. Schweinitzii Torr. Ann. Lye. N. Y. 3 : 276. 1836. 



Perennial by the thickened corm-like bases of the 

 culms, tufted, culms rather slender, rough, at least 

 above, i°-2i° tall, about equalled by the light green 

 leaves. Leaves l"-2i" wide, rough-margined, 

 those of the involucre 3-7, erect, the longer exceed- 

 ing the inflorescence ; umbel simple, 3-9-rayed, the 

 rays erect, sometimes 4' long; spikelets flat, in 

 rather loose ovoid spikes, which are sessile and at 

 the ends of the rays, linear-oblong, 6-12-flowered, 

 4"-8" long; scales convex, light green, ovate, acute 

 or acuminate, 9-13-nerved, falling away from the 

 rachis at maturity ; stamens 3 ; . style 3-clef t ; achene 

 sharply 3-angled, oblong, brown, acute at each end, 

 nearly as long as the scale, its superficial cells 

 quadrate. 



In sandy soil, especially along lakes and streams, west- 

 ern New York and southern Ontario to the Northwest 

 Territory, Iowa, Minnesota and Missouri. Aug.-Oct. 



12. Cyperus Houghtoni Torr. Houghton's 

 Cyperus. Fig. 732. 



C. Houghtoni Torr. Ann. Lye. N. Y. 3 : 277. 1836. 



Perennial by tuber-like conns, culms very slender, 

 smooth, erect, i°-2° tall. Leaves shorter than the culm, 

 1" wide or less, smooth, those of involucre 3-5, the 

 longer much exceeding the umbel; umbel simple, 1-5- 

 rayed, the rays mostly short, their sheaths 2-toothed; 

 spikelets loosely capitate, linear, compressed, acute, 

 4"-8" long, about 1" wide, n-15-flowered, falling away 

 from the axis when mature ; scales chestnut brown, 

 firm, somewhat spreading, shining, oblong, obtuse, trun- 

 cate or apiculate, strongly about n-nerved; rachis very 

 narrowly winged ; stamens 3 ; style 3-clef t ; achene 

 broadly oblong, less than twice as long as thick, 

 3-angled, brown, apiculate, nearly as long as the scale. 



In sandy soil, Massachusetts to Manitoba, Virginia, Mich- 

 igan and Wisconsin. July-Aug. 



