106 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



Perigynia rounded at both ends, circular in cross section. 

 Leaves firm, very glaucous; lower scales exceeded by the perigynia. 



64. C. glaucodea. 

 Leaves thin, soft, not glaucous; lower scales at least equaling the perigynia. 

 Spikes widely scattered; leaves 2-4 mm. wide, erect; perigynia scarcely turgid. 



65. C. amphibola. 



Spikes borne principally in the upper axils; leaves 4-6 mm. wide, spreading 



perigynia turgid 66. C. grisea. 



21. Laxiflorae Kunth. 



Flowering culms lateral; spikes more or less laxly flowered; perigynia subfusiform, 

 many-nerved . 



Perigynia sharply angled, short-tapering at the base. 

 Staminate scales dark brown or purplish; perigynia 5-7 mm. long. 



67. C. careyana. 

 Staminate scales straw-colored or pale brown; perigynia 2-4 mm. long. 

 Basal leaves 1-3 cm. wide; pistillate spikes sessile, erect; perigynia smooth. 



68. C. platyphylla. 

 Basal leaves usually narrower (if 1 cm. wide, the pistillate spikes llexuous on 



capillary peduncles); perigynia minutely roughened. 

 Scales blunt: staminate spikes sessile or nearly so; peduncles short, erect. 



69. C. abscondita. 

 Scales acuminate to aristate; staminate spikes usually strongly peduncled; 



lower peduncles capillary. 

 Perigynia 2.&-3.2 mm. long, short-beaked; leaves usually exceeding the 



culm, 2.5-5 mm. wide, erect 70. C. digitalis. 



Perigynia 3.3-4-mm. long, beakless or nearly so; leaves usually exceeded by 



the culm, 4-8 mm. wide, spreading 71. C. laxiculmis. 



Perigynia obtusely angled, long-tapering at the base. 

 Leaves 1,5-4 cm. wide; pistillate scales truncate. Culms flattened and wing-mar- 

 gined .72. C. albursina. 



Leaves 0.3-2 cm. wide; pistillate scales acuminate to strongly cuspidate. 



Spikes short, 5-10-flowered, the lower on capillary, spreading or drooping pedicels. 



73. C. styloflexa. 

 Spikes elongate, 8-20-flowered, the lower normally on stiff erect peduncles. 

 Perigynia obovoid; beak abruptly bent, minute; sterile shoots developing 

 conspicuous culms. 

 Staminate spike usually small and hidden among the pistillate, short-stalked 



or sessile; culms stout, winged 74. C. blanda. 



Staminate spike prominent, usually projecting above the pistillate, usually 



long-stalked; culms slender,. not winged 75. C. laxiflora. 



Perigynia ellipsoid-fusiform; beak straight or oblique, elongate; sterile shoots 

 reduced to mere tufts of leaves. 

 Culms stout, densely cespitose; basal leaves less than 30 cm. long, their 

 sides not parallel; perigynia appressed-ascending in an alternate-flowered 



spike 76. C. anceps. 



Culms slender, often loosely cespitose; basal leaves usually more than 30 cm. 

 long; perigynia spreading-ascending, mostly overlapping in the dense 

 spike 77. C. striatula. 



22. Granulares Bailey. 

 Perigynia brown, ascending, granular-roughened. 

 A single species 78. C. granulans. 



