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 



