1921 ] Smiley: Flora of the Sierra Nevada of California 111 



Spikelets several and densely flowered. 

 Perigynium long-beaked. 



Spikelets densely congested into a capitate cluster at top of 



culm 13. C. illota 



Spikelets, at least some of them, remote. 



Spikelets, except the terminal, somewhat globose or stellate 

 and scattered along the upper part of culm; scales 



ovate r 14. C. stellulata 



Spikelets oblong (up to % inch long) or linear-cylindrical; 

 scales acute and often hispidly awned ..15. C. Bolanderi 



Perigynium short-beaked 16. C. canescens 



Perigynium wing-margined. 



Spikelets aggregated into a more or less dense head. 



Bracts subtending the head greatly elongated 



17. C. athrostachya 



Bracts not greatly elongated, sometimes obsolete. 



Perigynium acuminately rostrate; scales obtusish 



18. C. Macloviana 



Perigynium abruptly rostrate; scales acute 



19. C. straminifonnis 



Spikelets more or less remote, at least some of them quite distinct. 

 Scales not scarious margined. 



Beak of perigynium short and wing smooth 



20. C. straminea var. mixta 



Beak of perigynium longer and wing scabrid ....21. C. specifica 

 Scales broadly scarious margined. 



Beak gradually attenuate, bidentate at the tip ....22. C. tahoensis 



Beak abruptly rostrate and deeply cleft 23. C. Liddouii 



B. 2 Stigmas 3, or rarely 2 and then at least some of the spikelets pedunculate. 

 Stigmas 2; achene plano-convex or lenticular in cross-section. 



Perigynium becoming fleshy when mature 24. C. aurea 



Perigynium not becoming fleshy when mature. 



Perigynium strongly ribbed 25. C. nebraskensis var. praevia 



Perigynium not strongly ribbed. 



Perigynium turgid; plants from stiff woody rootstocks; culms 

 stiff and obtusely angled; beak of perigynium minute and 



erect 26. C. rigida 



Perigynium not turgid; plants caespitose, sometimes with slen- 

 der rootstocks; culms weak and sharply angled. 

 Plant somewhat glaucous; spikelets short and thick 



27. C. Goodenovii 



Plant green; spikelets linear-cylindrical. 



Scales acutish, black, unmargined; plant 16-30 inches high. 



28. C. acutina 



Scales obtuse, dark red, scarious margined; plant 8-16 



inches high 29. C. Kelloggii 



Stigmas 3; achene triangular in cross-section. 



Leaves septate-nodulose, sometimes only slightly so. 



Perigynium more or less gradually tapering to the beak; culm 

 sharply angled below the spikelets and scarcely spongy at 



base 30. C. vesicaria 



Perigynium abruptly rostrate; culm obtusely angled, thick, and 



spongy at base 31. C. rostrata 



Leaves not septate-nodulose. 



Perigynium pubescent or hispid. 



Beak of perigynium entire; leaf and its sheath densely 



pubescent 32. C. yosemitana 



Beak of perigynium bidentate; leaf and its sheath nearly 

 glabrous or only scabrid on the margins. 



Beak of perigynium short 33. C. lanuginosa 



Beak of perigynium longer , 34. C. Congdoni 



Perigynium glabrous (except in var. brevipes of C. Rossi). 

 Upper spikelet bisexual, male at base. 



Spikelets all but the lowest sessile; culms rigid; scales purple 

 margined with yellow mid-nerve; perigynium prominently 

 nerved ... ....35. C. Buxbaumii 



