110 Karl M. Wiegand and Arthur J. Eames 



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i. Pistillate spikes all near the summit of the culm. 

 j. Leaves 2.5 mm. wide or less. 



k. Plant stoloniferous ; culms scattered; staminate spike 



prominent, 10-15 mm. long 59. C. pennsylvanica 124 



k. Plant cespitose, more slender ; staminate spike smaller, 



5-12 mm. long 60. C. varia 124 



/. Leaves 2.5-5.5 mm. wide; plant larger, cespitose. 



61. C. communis 125 



i. Pistillate spikes mostly half hidden among the densely tufted 



leaf bases, often also one or two near the staminate spike, 



rarely all stalked and exserted ; leaves 1-4.5 mm. wide. 



/. Beak of the perigynium about as long as the body ; culms 



usually 1-15 cm. high, with or without 1-2 pistillate spikes 



near the staminate spike 62. C. umbellata 125 



/. Beak of the perigynium relatively broader and only about 

 half the length of the body ; culms 1-5 cm. high, usually 

 bearing the staminate spike only. 



62a. C. u., var. brevirostris 125 

 h. Pistillate spikes drooping ; perigynia glabrous, 5-6 mm. long ; 

 beak very long and slender, much exceeding the body in length ; 

 plant 4-9 dm. high; (leaves 3-4 mm. wide) . 



63. C. longirostris 125 

 c. Lowest bract vaginate. 

 /. Perigynia ascending ; bracts ascending or erect ; basal sheaths pale 

 brown to purple. (2d /, p. 113.) 

 g. Spikes (0.5-4.5 cm. long) erect or ascending, or if strongly 

 drooping the perigynia either puberulent or 35-50-nerved ; peri- 

 gynia almost nerveless or 12-50-nerved, dull and glaucous, or 

 lustrous, apex straight or oblique ; terminal spike wholly stami- 

 nate, except sometimes in no. 66. (2d g, p. 112.) 

 h. Perigynia sparsely puberulent, strongly contracted and stipitate 

 below the middle, nearly nerveless ; scales truncate-aristate. 

 usually purple ; spikes scattered, drooping ; sheaths with very 

 short blades ; staminate spike and basal sheaths purple. 



60. C. pedunculata 125 

 h. Perigynia glabrous. 



i. Leaves 1 mm. wide or more ; staminate spike not overtopped 

 by the lower pistillate spikes. (2d i, p. 112.) 

 /. Perigynia sharply triangular, closely 35-50-nerved. 

 k. Spikes erect, nearly sessile ; culms erect or arching. 

 /. Cauline sheaths bladeless, more or less purple-tinged : 

 basal sheaths and staminate spike purple; leaves 1.5-3 



cm. wide, semi-evergreen 67. C. plantaginca 126 



/. Cauline sheaths blade-bearing, green. 



m. Perigynia 5-6.5 mm. long ; staminate spike dark ; 

 leaves 0.8-1.7 cm. wide, green or slightly glaucous ; 

 basal sheaths usually purple ; culms 3-7 dm. high. 



68. C. Careyana 126 

 m. Perigynia 2-4 mm. long ; staminate spike pale ; leaves 

 1-3 cm. wide, short, glaucous ; basal sheaths pale ; 



culms 1-3.5 dm. high 69. C. platyphylla 126 



k. Spikes drooping on filiform peduncles ; culms weak, 

 strongly arching ; sheaths and staminate spike pale. 



