62(60). Perigynia tightly filled to tip by achenes; base of style bulbous-thickened 

 59. C. eburnea. 



62. Perigynia not tightly filled by achenes, at least the summit usually empty 



(except for the style) (63) 



63(62). Bract at base of inflorescence (excluding rare basal spikes) sheathless 

 or barely sheathing (64) 



63. Bract at base of inflorescence with a prolonged closed and tubular sheath 



(76) 



64(63). Leaves and perigynia glabrous (65) 



64. Leaves (or sheaths) or perigynia or both pubescent (73) 



65(64). Perigynia compressed (C. serratodens may be plump), 1-2 mm. thick, 

 strongly appressed-ascending (at least before maturity) (66) 



65. Perigynia plump, 1.7-3.5 mm. thick, spreading to spreading-ascending (71) 



66(65). Pistillate scales small, acute to obtuse, 1.5-2.5 mm. long, persistent, 

 purplish-black; perigynia 2-2.5 (-3.5) mm. long 60. C. media. 



66. Pistillate scales larger or sharp-pointed or both; perigynia 3 mm. long or 



more (67) 



67(66). Terminal spike staminate 61. C. serratodens. 



67. Terminal spike gynecandrous, the terminal flowers pistillate (68) 



68(67). Perigynia densely papillose, glaucous-green, trigonous-biconvex; pistillate 



scales usually aristate, their tips exceeding the perigynia 



62. C. Buxbaumii. 



68. Perigynia puncticulate or granular but not papillose; pistillate scales not 



aristate (69) 



69(68). Perigynia not granular-roughened, the margins smooth; lower spikes on 

 long slender peduncles 63. C. bella. 



69. Perigynia granular-roughed, especially on the upper margins; spikes sessile 



or short-peduncled (70) 



70(69). Lowest spike slightly separate, short-peduncled; scales rough-papillose, 

 with very conspicuous white-hyaline apex and upper margins; apex 

 of perigynium body obtuse 64. C. albonigra. 



70. All spikes densely aggregated, sessile; scales with very inconspicuous hyaline 



margins; apex of perigynium body acute 65. C. nova. 



71(65). Terminal spike pistillate except at base; perigynia as broad as long, 

 transversely rugose 66. C. Shortiana. 



71. Terminal spike staminate; perigynia not transversely rugose (72) 



72(71). Pistillate scales gradually tapering or rounded to the awn; perigynia 4-5 

 mm. long, strongly ribbed 67. C. Joorii. 



72. Pistillate scales refuse and notched below the awn; perigynia 2.8-3.5 mm. 



long, essentially nerveless 68. C. glaucescens. 



73(64). Leaves septate-nodulose; perigynia densely soft-hairy 



69. C lanuginosa. 



73. Leaves or sheaths pubescent; perigynia not pubescent (74) 



74(73). Spikes usually 2 per culm, the lower ones 7-10 mm. thick; scales of 

 the lower part of the ovoid pistillate portion of the terminal spike 

 strongly cuspidate, 4-5 mm. long, longer than the perigynia; 

 perigynia 3-5 mm. long 70. C. Bushii. 



lA. Spikes usually 3 (sometimes 4) per culm, the lower ones 4—6 mm. thick; 

 scales of lower part of the ovoid-cylindric to cylindric pistillate 

 portion of the terminal spike 1.5-3 mm. long, shorter than or 

 equaling the mature perigynia; perigynia 1.8-2.8 mm. long (75) 



495 



