108 Karl M. Wiegand and Arthur J. Eames 



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h. Spikes crowded, closely flowered, not clavate-based ; perigynia 

 narrowly ovoid (2-3 mm. long, 1.2-1.7 mm. wide). 



39. C. Bebbii 121 

 h. Spikes distant, less densely flowered, clavate-based ; inflores- 

 cence usually flexuous and nodding ; perigynia ovoid. 

 t. Scales shorter than the perigynia, which are nerved or nerve- 

 less on the inner face. 

 j. Tips of the perigynia scarcely spreading; perigynia up to 



3.3 mm. long 40. C. tenera 121 



/. Tips of the perigynia spreading ; perigynia up to 4.5 mm. 



long 40a. C. t., var. echinodes 121 



i. Scales equaling or exceeding the perigynia, which are strongly 



nerved on the inner face 42. C. foenea 122 



e. Perigynia 2.3-2.5 mm. wide, the body suborbicular ; sheaths close ; 

 (scales shorter than the perigynia). 

 /. Perigynia 3.4 mm. long, the body very broadly ovoid or broadly 

 oval ; scales acute or blunt ; spikes 5-8 mm. long, rounded. 



41. C. brevior 121 

 /. Perigynia 4-5 mm. long, the body broadly obovoid ; scales attenuate 



or aristate; spikes large, 8-15 mm. long, ovoid-conic. . .43. C. alata 122 

 b. Spikes normally unisexual, the uppermost wholly or in part staminate, the 

 lower ones entirely pistillate or with a few staminate flowers at apex. 

 ( Eucarex. ) 

 c. Achenes lenticular ; stigmas 2. 

 d. Scales obtuse or acute, not aristate, rarely much exceeding the peri- 

 gynia, frequently brown or fuscous. 

 e. Perigynia compressed, green or brownish. 



/. Pistillate spikes drooping ; tips of the perigynia often twisted ; culms 

 smooth, from cord-like matted rootstocks; basal sheaths not fibril- 

 lose ; lower bract short 44. C. torta 122 



/. Pistillate spikes erect ; tips of the perigynia not twisted. 

 g. Culms from running rootstocks, nearly smooth ; basal sheaths not 

 fibrillose; plant very glaucous, substoloniferous; lower bract 



exceeding the staminate spike 45. C. aquatilis 122 



g. Culms in loose or dense stools, rough ; basal sheaths fibrillose ; 

 plants green or slightly glaucous, densely cespitose; lower bract 

 not exceeding the staminate spike. 



/;. Lowest pistillate spikes 3-7 cm. long 46. C. stricta 122 



/;. Lowest pistillate spikes 0.5-2.5 cm. long. 



46a. C. s., var. curtissima 122 

 e. Perigynia subglobose, salmon color or golden yellow when mature; 



(plant low, glaucous) 79. C. aurea 128 



d. Scales aristate or subulate-tipped, much longer than the more turgid 

 perigynia, pale ; pistillate spikes all peduncled and drooping. 

 e. Perigynia abruptly acute, widely spreading ; sheaths smooth ; larger 

 leaves 6-8 mm. wide. 

 /. Staminate spike wholly staminate; pistillate spikes 6-10 cm. long; 



scales abruptly long-awned 47. C. crinita 122 



/. Staminate spike usually part pistillate ; pistillate spikes 3-5 cm. long ; 

 scales from almost awnless to long- and rather abruptly-awned. 



47a. C. c, var. minor 123 

 e. Perigynia gradually acute, ascending ; scales gradually aristate ; 

 sheaths usually scabrous on back and on the hyaline part ; larger 

 leaves 7-11 mm. wide (5 mm. in small plants) 48. C. gynandra 123 



