166 



HORDKAK 



Some or all of the spikes distinct. 



Inflorescence merely interruptedly spicate or 

 paniculate. 

 Inflorescence of several small spikelets ses- 

 sile upon the central peauncle, form- 

 ing a compound spike. 

 Inflore.scence slender, 5 mm. wide or less, 

 interrupted. 

 Spikes 1- to 3-flowered; perigynia ellip- 

 soidal, erect; beak very short. 

 S-pikes 4- to 8-flowered; perigynia 

 ovate-lanceolate, divergent: beak 

 1-4 as long as the perigynium. 

 Inflorescence denser, 5 to 10 mm. wide, 



not appreciably interrupted. 

 Porig>-nia lanceolate, acuminate into a 

 long beak, strongly nervea. 

 Perigynia ovate, abruplly si;*;: 1 -beakecr. 

 weakly nerved. 

 Spikes with 1 to 5 perigynia, the lat- 

 ter 4 mm. long, not concealed by 

 the whitish scales. 

 Spikes with 5 to 10 perigynia, the lat- 

 ter 2.5 to 3.5 mm. long, mostly 

 concealed by the brownish scales. 

 Inflorescence of larger, ascending or spreading 

 spikes. 

 Lower spikes pedunculate. 

 Lower spikes not i^edunculate. 



Spikes crowded at the top of the peduncle. 

 Terminal spikes staminate. 

 Spikes all containing flowers of both 

 sexes. 

 Plants low, 4 to 6 inches high; spikes 



narrowly ovate-lanceolate. 

 Plants tall, 15 to 30 inches high; spikes 

 broadly ovate to orbicular. 

 Spikes scattered along the peduncle. 

 Perigynia narrowly wing-margined. 

 Beak bidentate, peringrynia brown. 

 Beak not bidentate, oblique. 

 Perigynia not wing-margined. 

 ' Perigynia abruptly contracted into a 



short beak, about 1-5 the length of 

 ■■ the body. 



Perigynia tapering into a beak 1-2 the 

 length of the body or more. 

 Perigynia not conspicuous, few in 

 each spike; scales straw-colored. 

 Perigynia conspicuous, about 10 in 

 each spike; scales brown. 

 Infloresecence of 2 to several distinct spikes. 

 Terminal splices not staminate; scales black. 

 Spikes 5 to 7 mm. long; peduncles less 



than 1 cm. long. 

 Spikes 10 to 15 mm. long; peduncles 1 to 

 5 cm. long. 



Terminal spike staminate; scales variously 

 colored (black in onie section). 



i^ 



16. C. tenella. 



17. C. interior. 



11. <J. stipata. 



1^ 



10. C. neomexicana. 

 9. C. occidentalis. 



7. C. agrostoides. 



j 

 2 6. C. pennsylvanica. 



?>. C. douglasii. 

 15. C. tribuloides. 



14. C. liddoni. 

 8. C. siccata. ^ 



4. C simulata. 



\y^ 



6. C latebrom, 

 5. C. marcida. • 



22. C, alpina. 

 24. C. bella. ■ 



