48 CYPERACEAE 



Scales dull with Inconspicuous nudvein, about covering the 

 perigynia. 126. C. atraUformis. 



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

 spikes oblong or linear-oblong or ovoid. 

 Perigynia granular-roughened; achenes short-stipitate. 



Upper pistillate scales exceeding the perigynia: lateral spikes 

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



127. C. chalciolepis. 

 Upper pistillate scales exceeded by the perigynia; lateral 

 spikes oblong or linear-oblong; lowest peduncle 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; perigynia .5 

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

 gynia. 130. C. Mertensii. 



41. ACUTAE. 



Culms phyllopodic. 



Beak of the perigynia, if present, not deeply bidentate. 



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

 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 Ught-colored center; culms taller, less stiff, in larger clumps. 

 Perigynia turgid, sjpreading. 134. C. aperta. 



Perigynia not turgid, appressed or ascending. 



Stolons absent; perigynia conspicuously nerved; leaf-blades 1-3 mm. wide. 

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



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



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

 only, the body half as wide as long. 136. C. Kelloggii. 



Stolons present, long; perigynia nerveless or inconspicuously nerved; leaf- 

 blades 2-6 mm. wide. 

 Perigynia narrowly to very broadly elliptic, broadest below apex, less 



than 3 mm. long, 1-1.5 mm. wide. 137. C. aguatilis. 



Perigynia strongly obovate, broadest at the apex, 3 mm. long, 1.75 mm. 

 wide. 138. C. substricta. 



Beak of the perigynia markedly bidentate, the body strongly ribbed. 



139. C. nebraskensis. 

 Fertile culms aphyllopodic. 



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



Lower sheaths strongly hispidulous ; scales blackish. 141. C. prionophylla. 



42. HlKTAE. 

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

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



Perigynia densely or strongly pubescent. 



Nerves of the perigynia obscured by pubescence, the teeth of beak short. 

 Leaf-blades flat, more than 2 mm. wide. 143. C. lanuginosa. 



Leaf-blades involute, 2 mm. wide or less. 144. C. lasiocarpa. 



Nerves of the perigynia prominent, the teeth of beak prominent, slender. 



145. C. Houghtonii. 

 Beak of the perigynia including teeth nearly as long as body, the teeth 1.5 mm. long or 

 more. 

 Perigynia glabrous. 



Perigynia ovoid, the teeth less than 2 mm. long, erect or spreading; scales acute 



to aristate; leaf-blades glabrous. 146. C. laeviconica, 



Perigynia lanceolate or ovoid-lanceolate, the teeth 2-4 mm. long, widely spread- 

 ing; scales long-aristate; leaf-blades pubescent beneath. 



147. C. atherodes 

 Perigynia hairy. 148. C. Sheldonii. 



43. EXTENSAE. 



Perigynia2-3 mm. long, thebeakscarcelyhalfaslongasthe body. 149. C. viridula. 

 Perigynia 4-6 mm. long, the beak about as long as the body. 150. C. flava. 



44. Pauciplorae. 

 Rhacheola present, conspicuously exserted; culms with many leaves. 



151. C. microglochin. 

 Rhacheola absent or rudimentary, not conspicuously exserted; culms with few leaves. 



152. C. pauciflora. 

 45. Psetjdo-Cypereae. 



Perigynia suborbicular in cross-section, more or less inflated. 153. C. hystricina, 

 Perigynia obtusely triangular, scarcely inflated, closely enveloping achene. 



154. C. comosa. 

 46. Physocarpae. 



I'erigynia scarcely inflated; beak entire or emarginate; stigmas normally two and achenes 

 lenticular. 

 Perigynia lanceolate; fertile culms fllamentose at the base; rootstocks creeping. 



155. C. miliaris. 



