CYPERACEAE. 



Scales much longer than the few, 1-6, perigynia. C. geyeri. 

 Scales not longer than the several to numerous 



perigynia. 



Perigynia broadly obtuse, beakless. C. leptalea. 



Perigynia narrowed to the bidentate apex. 

 Scales as long as or longer than the peri- 

 gynia. C. hepburm. 

 Scales shorter than the perigynia. C. circinata. 



Section II. VIGNEA. 



Spikes sessile, all alike, bearing the inconspicuous staminate flowers at the 

 base, at the top, or rarely scattered; stigmas 2, rarely 3; perigynia mostly 

 plano-convex; akenes lenticular. 



When the staminate flowers are below the pistillate, the base of the spike 

 is commonly contracted; when above the pistillate, the upper scales are 

 empty at maturity. 



Staminate flowers borne at the top of the spike. 



Perigynia plumo, nearly terete, pale green. C. tenella. 



Perigynia strongly compressed. 



Beak of perigynium much longer than the body. C. stipata. 

 Beak of perigynium shorter than the body. 



Spikes somewhat paniculate; perigynia brown, 



biconvex. C. cusickii. 



Spikes aggregated into a head. 



Stigmas 3; perigynia 12 mm. long. C. macrocephala. 



Stigmas 2; perigynia much smaller. 



Leaves equalling or exceeding the stem; 



head interrupted, 5-8 cm. long. C. vicaria. 



Leaves shorter than the stem; head 



densely ovoid. 

 Beak and top of perigynium rough on 



the angles. C. hoodii. 



Beak and top of perigynium smooth. 

 Perigynia elliptic, narrowly wing- 

 margined; seashore plant. C. pansa. 

 Perigynia ovate-lanceolate, not 



wing-margined; alpine plant. C. vernacula, 

 Staminate flowers at the base of each spike or rarely scat- 

 tered. 



Margins of perigynia not thin or winged. 

 Spikes crowded into a dense head. 



Head pyramidal, 5-10 mm. long; perigynia 



smootn on the margins. C. illota. 



Head oblong to ovoid, 15-30 mm. long; peri- 

 gynia strongly serrulate. C. arcta. 

 Spikes scattered. 



Perigynium 4-4.5 mm. long. C. bolanderi. 



Perigynium 2-2.5 mm. long. 



Perigynium not minutely puncticulate with 



white dots, somewhat spongy at base. C. laeviculmis. 



Perigynium minutely puncticulate with 



white dots, not spongy at base. 

 Herbage glaucous; perigynia many, as- 

 cending, obscurely beaked. C. canescens. 

 Herbage green; perigynia few, spreading, 



distinctly beaked. C. brunnescens. 



