70. 
9. Glumes 9- to ll-nerved; stamens 3.......... C. filicinus 
9. Glumes 3-nerved; stamens 1 or 2. Expected 
(C. pseudovegetus, C. fuscus). 
7. Rachilla winged; stamens 3. 
10. Spikelets not all deflexed, the uppermost 
ascending or spreading, 3- to 40-flowered 
(sometimes 2-flowered in C. ovularis). 
11. Achenes .8-1 mm. long; glumes 3- to 7- 
nerved. Expected (C. dentatus, C. erythro- 
rhizos). 
11. Achenes 1.3-3 mm. long; glumes 7- to 
many-nerved. 
12. Achenes 2.2-3 mm. long, 3 to 5 times 
as long as wide; glumes 4-5.5 mm. 
long. Expected (C. refractus, 
C. lancastriensis). 
12. Achenes 1.3-2 mm. long (rarely 2.2 
mm. in C. ovularis), ovoid to oblong; 
glumes 1.5-4 mm. long (rarely 4.5 mm. 
in C. strigosus). 
13. Spikelets 2- to 3-flowered, 
densely congested into subglobose 
heads at the ends of the rays; 
achenes 1.8-2.2 mm. long......- C. ovularis 
13. Spikelets 5- to 40-flowered, not 
in subglobose heads; achenes 
1.3-2 mm. long. 
14. Spikelets nearly flat; achenes 
linear, 1.5-1.8 mm. long; 
glumes 3.7-4.5 mm. long.... C. strigosus 
14. Spikelets subterete or sub- 
quadrangular; achenes ovoid 
to oblong, .5-1.2 mm. long; 
glumes 1.5-3.5 mm. long. Ex- 
pected (C. esculentus, C. grayii). 
10. Spikelets all deflexed at maturity, 1- or 
2-flowered. Expected (C. retrofractus, 
C. dipsaciformis). 
