STANDLEY — FLORA OF GLACIER PARK. 297 



Plants cespitose, the rootstocks short; spikes stamiuate at top or bottom. 

 Spikes staminate at top. 

 Spikes not very numerous, capitate; perigynia 4 to 5 mm. long, plano-convex, 



green, at least on margin 8. C. hcodii. 



Spikes very numerous, in a compound head; perigynia 2 to 2.75 mm. long. 



unequally biconvex, brown, shining 9. C diandra. 



Spikes (at least the terminal one) staminate at bottom. 

 Perigynia at most sharp-margined. 

 PerigjTiia spreading at maturity. 

 Perigynia broadest in middle, the beak sparingly serrulate; culms weak. 



10. C. laeviculmis, 

 Perigynia broadest near base, the beak strongly serrulate; culms stiff. 



11. C. interior. 



Perigynia appressed 12. C leptopoda. 



Perigynia narrowly to strongly wing-margined, the beak serrulate. 



Bracts conspicuous, exceeding the head 13. C. athrostachya. 



Bracts not conspicuous, shorter than the head. 



Scales about the length of the perigynia and of the same vndih above and 

 concealing them. 

 Perigynia with beak not hyaline at tip, flattened and serrulate nearly to tip. 



14. C. aenea. 



Perigynia with beak hyaline at tip, the tip terete and little if at all serrulate. 



Culms and head stiff and rigid; culms 10 to 30 cm. high, in large stools. 



16. C. phaeocephala. 

 Culms in clumps, slender; head flexuous or moniliform. 



Scales tinged with light reddish brown 17. C. praticola. 



Scales tinged with chestnut brown 18. C.piperi. 



Scales shorter than perigynia and narrower above, the upper part of the 

 perigynia conspicuous in the spikes. 



Perigynia with beak flat and serrulate to tip 15- C. bebbii. 



Perigynia with tip of beak terete and little if at all serrulate. 



Perigynia thin and flattened, except where distended by achene. 

 Perigynia 3.5 to 5 mm. long, appressed; culms tall, 20 to 70 cm. high. 



19. C. festivella. 

 Perigynia 4.5 to 6 mm. long, the beaks conspicuously spreading; 



culms low, 10 to 40 cm. high 20. C. nubicola. 



Perigynia strongly plano-convex, thick. 



Spikes densely capitate; perigynia with beak obliquely cut, dark- 

 tipped 21. C. pachystachya. 



Spikes not capitate; perigynia with beak bidentate, reddish-lipped. 



22. C. preslii. 

 CC. Perigynia white-puncticulate. 

 Spikes staminate at top; perigynia 1 to 5 to a spike, unequally biconvex. 



23. C. disperma. 



Spikes s'.aminate at bottom; perigynia more numerous, plano-convex. 



Perigynia broadest near middle; beak short, smooth or moderately serrulate. 

 Spikes closely approximate; scales strongly tinged with reddish brown; peri- 

 gynia with beak smooth or essentially so 24. C. lachenalii. 



Spikes not closely approximate, the lower spikes separated; scales little if at all 

 tinged with reddish brown; perigynia with beak usually more or less 



serrulate 25. C. canescens. 



Perigynia ovate, broadest near the base; beak conspicuous, strongly serrulate. 



26. C. arcta. 



