462 Key to the System of 



Fascicles of spikelets umbellate. 



Stems weak, very thin ; basal leaves flat, few or occasionally 

 undeveloped ; conspicuous floral leaves lax, four or fewer ; 

 spikelets few in each fascicle, flat ; floral bracts slightly 

 distant, acute, pale, with three venules ; stigmas three ; 

 fruit sharply triangular, smooth. C. trinervis. 



1963. Floral bracts about as long as broad, minute. 



Stems slender ; leaves mostly rather short, occasionally 

 undeveloped ; floral leaves one to three ; spikelets very 

 short and narrow, densely crowded into several partly 

 umbellate fascicles ; floral bracts numerous, dark-brown, 

 nearly orbicular ; stamens one or two ; stigmas three ; 

 fruit sharply triangular. C. difformis. 



Floral bracts longer than broad, small ... 1964 



1964. Root without any tubers. 



Stems slender, sometimes rather dwarf, always lax ; leaves 

 narrow ; conspicuous floral leaves three or four ; fascicles 

 of spikelets in a compound umbel ; spikelets much com- 

 pressed, few in each fascicle ; floral bracts laterally dark- 

 brown ; anthers very narrow ; stigmas three ; fruit 

 broadish, much shorter than its bract, pale, prominently 

 triangular. C. COUCiuutlS. 



Root producing tubers. 



Seldom tall ; leaves rather short ; conspicuous floral leaves 

 usually one or two ; fascicles of spikelets somewhat 

 spicate, forming a simple umbel or a solitary cluster ; 

 spikelets much compressed ; floral bracts brown, venular- 

 streaked ; stigmas three ; frait considerably shorter than 

 its bract, pointed, prominently triangular. 



C. rotundas. 



1965. Stems quite cylindrical. 



Seldom dwarf ; stems generally numerous, tough ; basal 

 leaves almost undeveloped ; floral leaves rigid, often 

 several, rarely much elongated ; spikelets crowded into 

 a solitary cluster or arranged into few or several umbellate 

 fascicles ; floral bracts laterally dark -brown, somewhat 

 pointed ; stigmas three ; fruit broadish, prominently 

 triangular. (C. textilis.) C. vaginatus. 



Stems conspicuously triangular ... ... ... 1966 



