112 CYPERACEAE 



^Spikes one to many; if one, plant not as above. 



Achenes lenticular and stigmas two; lateral spikes sessile; terminal spike partly 



pistillate, or if staminate, the lateral spikes short, or heads dioecious. 

 Spike one. 



Spike orbicular to short-ovoid. 4. CAPITATAE. 



Spike linear. 5. DIOICAE. 



Spikes more than one. 



Perigynia not white-puncticulate. 



Rootst9cks long-creeping, the culms arising singly or few together. 

 Perigynia not thin or wing-margined, the beak obliquely cut. 

 Culms not branching. 



Spikes densely aggregate into a globular-ovoid head, appearing 



like one spike. 6. FOETIDAE. 



Spikes distinct. 7. DIVISAE. 



Culms becoming decumbent and branching. 



8. CHORDORRHIZAE. 

 Perigynia thin or. wing-margined, the beak bidentate. 



9. ARENARIAE. 

 Rootstock not long-creeping, the culms densely cespitose. 



Spikes androgynous. 



Perigynia abruptly contracted into the beak. 



Spikes few (ten or less); perigynia green or tinged with reddish 

 brown. 10. MUHLENBERGIANAE. 



Spikes numerous; perigynia yellowish or brownish. 



Perigynia yellowish; opaque part of leaf-sheath transversely 



rugulose. 11. MULTIFLORAE. 



Perigynia brownish; opaque part of leaf-sheath not trans- 

 versely rugulose. 12. PANICULATAE. 

 Perigynia tapering into the beak. 13. STENORHYNCHAE. 

 Spikes gynaecandrous or pistillate or rarely staminate. 

 Perigynia at most thin-edged. 



Perigynia spreading at maturity. 14. STELLULATAE 



Perigynia appressed. 15. DEWEYANAE. 



Perigynia narrowly to broadly wing-margined. 



16. OVALES. 



Peiigynia white-puncticulate. 17. CANESCENTES. 



Achenes triangular or lenticular; if lenticular, lower lateral spikes conspicuously 



peduncled, or terminal spike staminate and lateral spikes elongated. 

 Achenes strongly constricted at base, rounded at apex. 18. PHYLLOSTACHYAE. 

 Achenes not strongly constricted at base, pointed at apex. 



Spike one; perigynia rounded and beakless at apex. 19. POLYTRICHOIDEAE. 

 Spikes one or more; when one, perigynia not both rounded and beakless at 



the apex. 



Perigynia both coriaceous and shining, the beak obliquely cut. 

 Spike solitary. 20. OBTUSATAE. 



Spikes several. 21. NITIDAE. 



Perigynia not both coriaceous and shining. 



Spike one; perigynia triangular, glabrous, not reflexed or flattened. 

 Perigynia prominently beaked, finely many-nerved. 



22. RUPESTRES. 



Perigynia nearly beakless, 2-keeled but otherwise nerveless. 



23. FlRMICULMES. 

 Spikes one to many ; when one, perigynia differing from above. 



Perigynia closely enveloping the achene, strongly tapering at base, 



ubescent or puberulent; bracts sheathless or nearly so. 

 3 normally one. 

 Spikes androg\ nous ; leaf-blades very narrow. 



24. FILIFOLIAE. 

 Spikes dioecious. 25. SCIRPINAE. 



Spikes two or more. 26. MONT AN AE. 



Perigynia not as above; or if so, bracts strongly 'sheathing. 

 Lowest bract long-sheathing, its blades rudimentary. 

 Leaf-blades flat; perigynia puberulent or pubescent. 



27. DlGITATAE. 



Leaf-blades filiform; perigynia glabrous. 



28. ALBAE. 



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 two. 29. BICOLORES. 

 Achenes triangular; stigmas three. 

 Scales not dark-tinged. 



Pistillate spikes short-oblong to linear, erect. 



Perigynia tapering at base, triangular, closely 



enveloping the achenes. 

 Rootstock long-creeping. 



30. PANICEAE. 

 Rootstock not long-creeping. 



31. LAXIFLORAE. 



