CYPERACEAE 23 
Staminate flowers above the pistillate, rarely mixed with them. 
Spikes forming a globose head. 
Perigynia about 2 mm, long. 
Beak entire, edges not serrate. 31. C. stenophylla. 
Beak 2-toothed, edges serrate. 42. C. cephalophora. 
Perigynia 3 mm. long, or more, 
Scales half as long as perigynia. 41. C, cephaloidea. 
Scales as long as perigynia, or longer. 
Scales 2-4 times as long as perigynia. 32, C. douglassli. 
Scales little longer than perigynia. 43. C. muhlenbergia. 
Spikelets not forming globose heads. 
Perigynia over 3 mm. long, or scale only half as long as the 
perigynium, 
Beak of Perigynium much longer than body, usually 2-4 
times as long. 
Base of perigynium not thickened, beak about twice as 
long as body of perigynium. 33. C. stipata. 
Base of perigynium thickened, disc-like, beak 3-4 times 
as long as the. body. 34. C. crus-corvi. 
Beak of perigynium short, about half as long as the body. 
Scales equal to or longer than the perigynia: 
Perigynium wing-margined. 43. C. muhlenbergia. 
Perigynium not wing-margined. 37, C. gravida. 
Seales about half as long as perigynia. : 
Leaves 1-3 mm, wide. 39. C. rosea. 
Leaves 4-9 mm. wide. 
Perigynium wing-margined to the base, spikes not 
in heads. 40. C. sphagnoides.. 
Perigynium wing-margined only above the middle, 
spikes approximate in cylindrical heads. 
41. C. cephaloldea. 
Perigynia about 2 mm. long or less. 
Spikes yellow or brown at maturity. 
Leaves less than 2 mm. wide. 
Beak of perigynium shorter than body. 35 C, marcida. 
Beak of perigynium as long as body. 
36. C. teretluscula. 
Leaves 2-5 mm. wide. 38, C. vulpinoides. 
Spikes green or greenish at maturity. 42. C. cephalophora.. 
Staminate flowers below the pistillate, sometimes mixed with them 
in C. siccata. 
Perigynia lanceolate, wing-margined. 
Wings broad, scales*‘as long as perigynia. 44, C. siccata.. 
Wings narrow, scales shorter than perigynia. 
Spikes oblong or oval. 
Spikes blunt, greenish brown. 45. C. tribuloldes. 
Spikes pointed, bright brown. 46. C. scoparia. 
Spikes subglobose. 47. C. cristatella. 
Perigynia ovate or orbicular, its body as wide as long. 
Beak as long as body of perigynium. 48. C. straminea. 
Beak not over half as long as body. 
Heads brownish achene sessile. 49. C. festucea.. 
