118 C YPER ACE AE 



Culms many-leaved, clothed at base -with dried-up leaves of previous year, not 



purplish tinged at base. ^ r^ , . . 



Perigynia flat. 118- C. Tolmiet ,, 



Perigypla round in cross-section, many-nerved. 119. C. Raynoiasti, 



Terminal spike gjTiaecandrous. 

 ' Perigynia triangular in cross-section, nerveless or nearly so. 2.5 mm. long or less. 



120. C. Halleri. 

 Perigynia longer, many-nerved or with two prominent marginal nerves, more or 



less strongly flattened. , 



Spikes contiguous, sessile or short-peduncled, forming a dense head; cuims 



stjitT Greet 

 Perig\Tiia subinflated-triangular, scarcely compressed, the beak 1 mm. 



long. 121. C. Nelsonii. 



Perigynia strongly compressed, the beak 0.5 mm. long. 



Lowest spike slightly separate, short-peduncled; scales black, "VMtn 

 very conspicuous white hyaline apex and upper margins. 



122. C. albo-mgra.^ 

 Spikes closely contiguous and sessile; scales black with inconspicuous 

 hyaline apex and margins. 123. C. nova. 



Lowest spike (or spikes) strongly peduncled, usually distant, erect or nodamg. 

 Spikes 3-5, not oblong-cylindrij; walls of the perigynia not papery; peri- 

 gynia 2.5-4.5 mm. long, nerveless or obscurely nerved on the ^?rf' 

 dull green to brownish black; scales from a little shorter to a httie 

 longer than the perigynia. , 



Perigynia slightly inflated and sub-triangular, not strongly compressea. 



124. C. atrosquama. 



Perigynia strongly compressed. , 



Perigynia sharp-edged, the margins much narrower than the acnene, 



lateral spikes linear. , i i tv. 



Scales shining, with the midvein conspicuous the whole lengtn, 



exceeded by the perigynia. 125. C. bclla. 



Scales dull with inconspicuous midvein, about covering tne 

 perigynia. 126. C. atratiformxs. 



Perigynia widely margined, the margins as wide as the achene ; lateral 



spikes oblong or linear-oblong or ovoid. 

 Perigynia granular-roughened; achenes shorfc-stipitate. 



Upper pistillate scales exceeding the perigynia: lateral spiKes 

 ovoid; lowest peduncle less than the length of the spUie. 



127. C. chalciolepis. 

 Upper pistillate scales exceeded by the perigynia; lateral 

 spikes oblong or linear-oblong; lowest pedimcle 1-2 times 

 as long as the spike. 128. C. atrata. 



Perigynia smooth; achenes strongly stipitate. 



129. C. epapillosa. , 



Spikes 6-10. oblong -cylindric: walls of the perigynia papery; peng>Tuaj> 

 mm. long, lightly 3-nerved. light green, much shorter than the pen- 

 g>Tiia. 130. C. Mertensit, 



41. ACXJTAE. 



Culms phyllopodic. 



Beak of the perigjmia. if present, not deeply bidcntate. . j 



Lowest bract exceeded by the inflorescence; scales with obsolete or slender mia- 



vein; culms low, stiff, solitary or in small clumps, freely stoloniferous. 

 Perigynia plano-convex, puncticulate, appressed. 131. C concolor. 



Perigynia soon turgid, papillose, spreading. 



Scales ovate, exceeded by the perigynia. 132. C, scopulorum. 



Scales lanceolate, exceeding the perigynia. 133. C. chimaphila^ , 



Lowest bract exceeding the inflorescence; scales usually with a slender mid vein or 



broad light-colored center; culms taller, less stitT, in larger clumps. 

 Perigynia turgid, spreading. 134. C. aperta. 



Perigynia not turgid, appressed or ascending. . , 



Stolons absent; perigynia conspicuously nerved; leaf-blades 1-3 mm. ^'^".^• 

 Perigynia substipitate, glaucous, granular-roughened all over, tne 



body two-thirds as wide as long. 135. C Uniicularis. 



Perigynia strongly stipitate. green, granular-roughened at the apex 

 only, the body half as wide as long. 136. C. Kellogon* , 



Stolons present, long; perigynia nerveless or inconspicuously nerved; it'^^" 



blades 2-6 mm. wide. , 



Perig^-nia narrowly to very broadly elliptic, broadest below apex, less 



than 3 mm. long. 1-1.5 mm. wide. 137. C. aQualilis- 



Perigynia strongly obovate, broadest at the apex. 3 mm. long, 1.7o mm. 

 wide, 138. C. substricta. 



Beak of the perig3maa markedly bidentate. the body strongly ribbed. 



139. C. nebraskensis. 



Fertile culms aphyllopodic. 



Lower sheaths smooth; scales not blackish. 140. C. Ejnoryi. 



Lower sheaths strongly iiispidulous ; scales blackish. 141. C. prionophylla, 



42. HlRTAE. 



Beak of the perigynia much shorter than the body, the teeth 1 mm. long or less. 

 Perigiiiia glabrous to sparsely pubescent. 142. C. lacustris. 



