114 CYPERACEAE 



7. DiVISAE. 



Rootstocks slender, light brownish; culms obtusely triangular, normally smooth; leaf- 

 blades narrowly involute. 

 Perigynia long-beaked ; heads dioecious or nearly so. 10. C Douglasii, 



Perigynia short-beaked; heads androgynous. 11. C. stenophylla. 



Rootstocks stout; culms acutely triangular, normally rough above. 

 Perigj-nia not strongly nerved ventrally; leaf-sheaths hyaline. 



Perigynia chestnut, thick, the beak about one-fifth as long as the body. 



12. C. simidata, 

 Perigynia blackish in age, plano-convex, the beak one-third to one-half as long as 

 ^ the body. 13. C. praegracilis. 



Perigynia strongly nerved ventrally; upper leaf-sheaths green-striate opposite the 

 blades. 14. c. SartwelUi, 



8. Chokdorrhizae. 

 Represented by one species in our range. 15. C. chord or rhiza. 



9. Arexariae. 



Represented by one species in our range. 16. C. siccata. 



10. MtfllLENBERGIANAE. 



Sheaths tight, inconspicuously, if at all. septate-nodulose. 



Densely cespitose; head ovoid, capitate; perigynia serrulate to the middle. 



17. C. Iloodif. 

 Rootstocks elongate; head linear, interrupted; perigynia serrulate at the apex only. 

 Scales obtuse to short-cuspidate, not concealing the spreading perigynia. 



Spikes with conspicuous staminate fiowers; scales half as long as the perigynia. 

 ^ ' 18. C. vallicola. 



Spikes with mconspicuous staminate flowers; scales about as long as the peri- 

 gynia. 19. c, occidentalis. 

 Scales strongly cuspidate, concealing the appressed perigynia. 

 _,, , , 20. C. Ilookeriana. 

 bheaths loose and membranous, easily breaking, conspicuously septate-nodulose. 



21. C gravida, 



11. MULTIFLORAE. 



Represented by one species in oiu" range. 22. C. vulpinoidea, 



12. Paxiculatae. 



Culms loosely cespitose; sheaths not copper-tmged at the mouth; head little interrupted; 



perigynia 2-2.75 mm. long, shining, not concealed by the scales. 

 „ , , _ . 23. C. diandra. 



culms densely cespitose; sheaths copper-tinged at the mouth; head interrupted; pen- 



gyma 2.5-4 mm. long, dull, concealed by the scales. 

 Leaves 1-2.5 mm. wide; perig>Tiia 2.5-3 mm. long; scales tinged with reddish brown. 



T ^ ^ ^ . , . 24. C. prairea. 



Leaves 2.5-6 nun. wide; perigynia 3-4 mm. long; scales chestnut-tmged. 



25. C. Cusickii. 



13. STENORnTXCHAE. 



PerigjTiia 3-4 mm. long, the beak much shorter than the body; scales strongly dark- 



tmged. 



Leaves clustered at base; sheaths not cross-rugulose ventrally; culms slender. 



* - 26. C. Jonesii. 



i^eaves not clustered at base; sheaths cross-rugulose ventrally; culms stout. 



-o . ' A ^ , 27. C. nervina. 



Perigyma 4-6 mm. long, the beak longer than the body; scales not dark-tinged. 



28. C. slipata. 



14. Stellulatae. 



Spikes in a small (6-10 mm. long) densely capitate brownish black head. 



Q^i «, 1 .^ , 29. C. illota. 



Spikes more or less widely separate, not brownish black 



Perigynia broadest in middle, the beak sparingly serrulate; culms weak. 



T, . ■ . , , , ^ , 30. C. laeviculmis. 



Per^yma broadest near base, the beak strongly serrulate; cuhns stiff. 



iieak ol the perigynia one-fourth as long as the body, the teeth short, and ventral 



suture mconspicuous. 31 c interior. 



Beak of the perigynia longer, strongly bidentate, the ventral suture conspicuous. 



32. C\ angustior^ 



15. Deweyanae, 



^^*J^i K^H^®'^ cespitose: perigynia tapering at base. 4-5 mm. long, the upper part of 

 ^r.lY% ^^^^ covered by translucent scale. 33. C. Dewegana 



^!l?.?^-^^®S^n''* ^^o?^?ate; perigynia substipitate. 3.5^.5 mm. long. 

 I'engjTiia shallowly bidentate, the upper part of body not covered bv the scale. 



n • » J 1 ^. , 34. C leptopoda. 



Perigynia deeply bidentate. the body covered by the scale. 35. C. Bolanderi. 



16. OVALES. 



^^'^^L,v,^iL^^^^''^*^i^ conspicuous, several-many times the length of the head. 



Peng>-ma subulate, the beak much longer than body; lower bracts more than 1 dm. 



long, without yellowish brown margins at base. 36. C. sgchnocephala. 



