207 l CYPERA.CEAE 



A. Spike one, androgynous, bractless; perigynia glabrous, beaked, the beak with closed 



suture at apex dorsally. 

 Achenes triangular; stigmas three, rarely two. 



Pistillate scales persistent; perigynia inflated, sessile, not becoming reflexed.l. INPLATAE. 

 Pistillate scales deciduous; perigynia not inflated, stipitate, at least the lower reflexed at 



maturity 2. ATHROCHLAENAE. 



Achenes lenticular ; stigmas two 3. CAPITATAE. 



B. Spikes one to many; if one, not as in A. 



1. Achenes lenticular and stigmas two; lateral spilces sessile; terminal spike partly pistillate, 



or if staminate the lateral spikes short or heads dioecious. 



Perigynia not white-puncticulate. 



Bootstocks long-creeping, the culms arising singly or few together; perigynia with beak 

 obliquely cut, at most bidentulate. 



Spikes densely aggregated into a globose or ovoid head, appearing like one spike 



4. FOETIDAE. 



Spikes, at least the lower, distinct 5. DIVISAE. 



Cespitose or rootstocks short-creeping; perigynia obliquely cut to deeply bidentate. 

 Spikes androgynous (i.e., staminate flowers uppermost). 

 Perigynia abruptly contracted into the beak. 



Spikes few (usually ten or less) ; perigynia green or tinged with reddish-brown. 



6. MTJHLENBERGIANAE. 

 Spikes numerous ; perigynia yellowish or brownish at flowering. 



Perigynia yellowish; opaque part of leaf -sheath usually transversely rugulose. 



7. MUI/TIFLORAE. 

 Perigynia brownish; opaque part of leaf -sheath not transversely rugulose. 



8. PANICULATAE. 

 Perigynia tapering into the beak 9. STENORHYNCHAE. 



Spikes gynaecandrous (i.e., pistillate flowers uppermost). 

 Perigynia at most thin-edged. 



Perigynia spreading or ascending at maturity 10. STELLULATAE. 



Perigynia appressed 11. DEWEYANAE. 



Perigynia narrowly to broadly wing-margined 12. OVALES. 



Perigynia white-puncticulate. 13. CANESCENTES. 



2. Achenes triangular and stigmas three, or lenticular and stigmas two; if lenticular, lower 



lateral spikes conspicuously peduncled, or terminal spike staminate 

 and lateral spilces elongated. 



Staminate and pistillate spikes on different culms; stigmas 3, short 17. SCIKPINAE. 



Staminate and pistillate spikes on the same culms. 

 Spike solitary. 



Perigynia many-nerved, rounded and beakless at apex; stigmas 3, short 



14. POLYTRICHOIDEAE. 



Perigynia 2-keeled, not rounded at apex, beakless or beaked. 



Perigynia glabrous; stigmas 3, elongated 15. FIRMICULMES. 



Perigynia pubescent or puberulent; stigmas 3 16. FILIFOLIAE. 



Spikes more than one. 



Perigynia closely enveloping the achene, strongly tapering at base, pubescent or puberu- 

 lent; bracts sheathless or nearly so; stigmas normally 3, long 18. MONTANAE. 



Perigynia not as above; or if so, at least the lowest bract strongly sheathing. 



Bracts (at least lowest) long-sheathing, more or less purplish-tinged, the blades 



absent or rudimentary; stigmas 3, early deciduous 19. DIGITATAE. 



Lowest bract sheathless or long-sheathing; if long-sheathing its blade well-developed. 

 Lowest bract strongly sheathing; perigynia never strongly bidentate with stiff 

 teeth. 



Achenes lenticular; stigmas 2 20. BICOLOBES. 



Acheues triangular; stigmas 3. 



Scales greenish or light reddish-brown or purplish tinged. 



Rootstocks long-creeping; scales purplish tinged 21. PANICEAE. 



Rootstocks not long-creeping; scales greenish to reddish-brown tinged. 

 Perigynia glabrous or hispidulous; leaves not pubescent. 



Pistillate spikes erect on stiff peduncles 22. LAXIFLORAE. 



Pistillate spikes slender on slender peduncles, the lower droop- 

 ing _ 24. DEBILES. 



Perigynia or leaves or both strongly pubescent 23. TRIQTJETRAE. 



Scales dark reddish-brown to blackish tinged 25. FRIGIDAE. 



Lowest bract sheathless or sheathing; if sheathing, perigynia strongly bidentate 

 with stiff teeth. 





