16 THE GENUS CAREX IN CALIFORNIA 



28. Acutae. 



I. Flowering culms arising from the center of previous year's tuft of leaves and surrounded at base 



with dried-up leaves of previous year. 



A. Lower sheaths of flowering culms not breaking and becoming filamentose. 



Strongly stoloniferous, the culms arising one-few together, low; lowest bract normally much 

 shorter than inflorescence; scales with obsolete or slender midvein. 

 Dried first year leaf-blades at base of fertile culms stiff, rigid and conspicuous, concealing the 

 culms; fertile culm leaves all blade-bearing, the lower sheaths not purplish or his- 

 pidulous dorsally 97. C. scopulorum. 



Dried first year leaf-blades at base of fertile culms much desiccated, not stiff, rigid or con- 

 spicuous, and not concealing the culms; lowest fertile culm leaves not blade-bearing, 



the lower sheaths purplish and more or less strongly hispidulous dorsally 



98. C. gymnoclada. 



Culms taller, less stiff, in larger clumps; lowest bract equaling or exceeding inflorescence; scales 

 with slender midvein or broader light colored center. 

 Perigynia strongly nerved ventrally, the nerves raised. 



Perigynia coriaceous, sessile or nearly so. the beak bidentate; strongly stoloniferous 



99. C. nebraskensis. 



Perigynia membranaceous, more or less slenderly stipitate, the beak entire; cespitose. 

 Perigynia substipitate, orbicular, minutely papillate-roughened; scales deciduous. 



100. C. paucicostata. 



Perigynia strongly stipitate, ovate. 



Perigynia yellowish-green, ribbed, papillate-roughened; scales deciduous 



101. C. Hindsii. 



Perigynia light green or in age glaucous green, nerved, very minutely granular; 



scales long persistent 102. C. Kelloggii. 



Perigynia nerveless ventrally or with obscure impressed nerves. 



Sheaths colored ventrally at mouth; lower pistillate spikes subcernuous on long peduncles; 



scales in age whitened at tip 103. C. sitchensis. 



Sheaths not colored ventrally at mouth; lower pistillate spikes not nodding; scales not 

 whitened at tip 104. C. aquatilis. 



B. Lower sheaths of flowering culms breaking and becoming filamentose. 



Beak of perigynium bidentate, hispidulous between teeth; scales strongly rough-awned 



*. 105. C. barbarm. 



Beak of perigynium entire or emarginate, not hispidulous between teeth; scales not rough-awned. 

 Lower culm sheaths strongly yellowish-brown tinged, sharply keeled; culms stout, the leaf- 

 blades 6-12 mm. wide 106. C. Schottii. 



Lower culm sheaths purplish-tinged, not sharply keeled; culms more slender, the leaf-blades 

 narrower 107. C. senta. 



II. Some or all of the flowering culms arising laterally and not enveloped at base by previous year's 



tuft of leaves. 



Culms very densely cespitose, forming dense stools; lowest sheaths strongly filamentose; lowest bract 



little developed, usually much exceeded by inflorescence 108. C. nudata. 



Culms much less densely cespitose, forming beds, conspicuously stoloniferous; lowest bract well- 

 developed from somewhat shorter-than to exceeding inflorescence. 



Perigynia orbicular or nearly so 109. C. eurycarpa. 



Perigynia oblanceolate 110. C. oxycarpa. 



29. Cryptocarpae. 



Perigynia dull, straw-colored or light brown, slightly granular; lower sheaths of sterile shoots not 



filamentose 111. C. Lyngbyei. 



Perigynia shining, brown, smooth; lower sheaths of sterile shoots strongly filamentose. 112. C. obnupta. 



