CYPERACEAE. 63 



3. ARGYRANTHAE. 



Spikes several, short and loose-flowered, sessile, remote, silvery to light- 

 green, gynaecandrous ; bracts short; scales hyaline; perigynium erect, mem- 

 branaceous, light-green, stipitate, lanceolate, nerved, serrate along the mar- 

 gins, tapering into a long bidentate beak. 



One species. 4. C. Deweyana. 



4. ASTROSTACHYAE. 



Spike single or several, short and few-flowered, sessile, remote; bracts 

 short and narrow ; scales brownish ; perigynium sessile, spreading at matur- 

 ity, cordate to ovate, several-nerved, spongious at base, tapering into a ser- 

 rate, bidentate beak. 



Spike single, unisexual or androgynous. 5. C. gynocrates. 

 Spike several, gynaecandrous. 



Perigynium narrowly ovate, faintly nerved. 6. C. stellulata. 



Perigynium broadly ovate, prominently nerved. 7. C. sterilis. 



5. ACANTHOPHORAE. 



Spikes several, short, but dense-flowered, sessile, androgynous ; bracts often 

 long; scales greenish to brown; perigynium slightly spreading, elliptical and 

 acuminate to suborbicular, faintly nerved or nerveless, spongious at base, 

 narrowly winged, the beak serrulate, bidentate. 



Spikes green, forming a dense, decompound panicle. 8. C. vulpinoidea. 

 Spikes forming a spike or head. 

 Inflorescence spicate. 



Spike interrupted. 9. C. Hookeriana. 



Spike contiguous. 10. C. occidentalis. 



Inflorescence capitate. n. C. Hoodii. 



6. XEROCHLAENAE. 



Spikes many, small, in a dense-flowered spicate inflorescence, sessile, con- 

 tiguous, androgynous or dioecious ; bracts often conspicuous ; scales brown- 

 ish ; perigynium stipitate, erect, ovate to lanceolate, nerved, brown, winged, 

 serrulate along the margins, tapering into a distinct, bidentate beak. 



Scales acuminate. 



Perigynium ovate, acuminate; spikes often unisexual. 12. C. marcida. 



Perigynium lanceolate; spikes bisexual. 13. C. Sartwellii. 



Scales awned, perigynium ovate-lanceolate ; spikes mostly unisexual. 



14. C. Douglasii. 



7. PHAENOCARPAE. 



Spikes small, many in an interrupted spicate inflorescence, sometimes pan- 

 iculately branched, sessile, contiguous or nearly so, androgynous ; bracts in- 

 conspicuous; scales brownish; perigynium somewhat spreading, ovate, 

 nerved, shining brown, spongious at base, the beak serrulate, bidentate. 



One species. 15. C. teretiuscula. 



8. ATHROSTACHYAE. 



Spikes several, but not many, in a dense-flowered spike or head, sessile, 

 gynaecandrous; bracts seldom conspicuous; scales brownish; perigynium 



