42 CYPERACEAE 



Spikes more than one. 



Perigyma not wbite-pnncticulate. 



Rootstocks 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. Foetid.\e. 



Spikes distinct. 7. Divisae. 



Culms becoming decumbent and branching. 8. Chordorrhiz.\e. 

 Perigynia thin or wing-margined, the beak bidentate. 



9. Arenariae. 

 Rootstock not long-creeping, the culms densely cespitose. 

 Spikes androgjTious. 



Perigj-nia abruptly contracted into the beak. 



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

 brown. 10. Muhlenbergiaxae. 



Spikes numerous; perigynia yellowish or brownish. 



Perigynia yellowish; opaque part of leaf-sheath transversely 



rugulose. 11. RIultiflorae. 



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

 versely rugulose. 12. Panicul.\tae. 

 PerigjTiia tapering into the beak. 13. Stenoriiynchae. 

 Spikes gjmaecandrous or pistillate or rarely staminate. 

 Perigj-nia at most thin-edged. 



PerigjTiia spreading at maturity. 14. Stellul.\tae. 



PerigjTua appressed. 15. Deweyanae. 



PerigjTiia narrowlj' to broadly wing-margined. 



16. OVALES. 



Peiigynia white-pimcticulate. 17. Canescentes. 



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

 ped uncled, or terminal spike staminate and lateral spikes elongated. 

 Achenes strongly constricted at base, romided at apex. 18. Phyllostaciiyae. 

 Achenes not stronglj' constricted at base, pomted at apex. 



Spike one; perigjTiia rounded and beakless at apex. 19. Poi.ytrtchoipe.^E. 

 Spikes one or more; when one, perigjTua 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; perigjTiia triangular, glabrous, not reflexed or flattened. 

 PerigjTiia prominently beaked, finely manj^-nerved. 



22. RurESTRES. 

 PerigjTiia nearlj' beakless, 2-keeled but otherwise nerveless. 



23. FiRMICULMES. 



Spikes one to manj-; when one, perigynia differing from above. 



PerigjTiia closelj- enveloping the achene, strongly tapering at base, 

 pubescent or pubenilent; bracts sheathless or nearlj- so. 

 Spike normally one. 



Spikes androgynous; leaf-blades verv narrow. 



24. FiLIFOLI.AE. 



Spikes dioecious. 25. Scirpix.ae. 



Spikes two or more. 26. Moxtanae. 



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

 Lowest bract long-sheathing, its blades rudimentarj-. 

 I^eaf-blades flat; perigynia puberulent or pubescent. 



27. DlCITATAE. 



Tieaf-blades filiform; perigynia glabrous. 



28. Albae. 



Lowest bract sheathless or long-sheathing; if long-sheathing, its 

 blade well-developed. 

 Lowest bract strongly sheathing; perigj-nia never strongly 

 bidentate with stiff' teeth. 

 Achenes lenticular; stigmas two. 29. BICOLORE.S. 

 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-creeoing. 



31. L.AXIFLORAE. 



Perigynia rounded at base, suborbicular in 

 cross-section, looselj' enveloping achenes. 



32. Gr.\nul.vres. 

 PistUlate spikes elongate, linear to cylindric, 



slender pedimcled, the lower drooping. 

 Culms strongly reddish tinged at base, aphyl- 



lopodic. 33. Debiles. 



Culms not strongly reddish tinged at base, 



phjilopodic. 



