170 MISC. PUBLICATION 4 2 3, U. S. DEPT. OF AGRICULTURE 



21. Perigynia not wing-margined, plano-convex or unequally bicon- 

 vex (22). 

 22. Culms obtusely angled or obtusely triangular, the rootstocks 

 slender; leaf blades narrowly involute or canaliculate (23). 

 23. Perigynia long-beaked; heads dioecious or nearly so. 



1. C. DOUGLASII. 



23. Perigynia short-beaked; spikes androgynous. 



2. C. ELEOCHARIS. 



22. Culms sharply triangular; leaf blades flat or channeled (24). 



24. Rootstocks slender; lower sheaths light brownish; perigynia 



chestnut-colored, unequally biconvex, 1.75 to 2.25 mm. 



long 3. C. SIMULATA. 



24. Rootstocks stout; lower sheaths dark brown or black; peri- 

 gynia blackish in age, plano-convex, 3 to 4 mm. long. 



4. C. PRAEGRACILIS. 



20. Culms from loosely to densely cespitose, the rootstocks sometimes 

 short-prolonged, but not long-creeping (25) . 

 25. Spikes androgynous (26). 



26. Perigynia with the body tapering into the beak. 



11. C. STIPATA. 

 26. Perigynia with the body abruptly contracted into the beak (27) . 

 27. Spikes 10 or fewer, appearing greenish (28). 



28. Beak of the perigynium obliquely cleft dorsally, little or 

 not at all bidentate; perigynia usually 1 to 5. 



6. C. RUSBYI. 



28. Beak of the perigynium bidentate; perigynia usually 5 to 



10 7. C. OCCIDENT ALIS. 



27. Spikes numerous, appearing yellowish (29). 



29. Scales not at all or but little hyaline-margined. 



10. C. VULPINOIDEA. 



29. Scales strongly hyaline-margined (30). 



30. Perigynia sharp-margined above, blackish at maturity. 



8. C. ALMA. 

 30. Perigynia sharp-margined to the base, straw-colored. 



9. C. AGROSTOIDES. 



25. Spikes gynaecandrous (31). 



31. Perigynia at most thin -edged (32). 



32. Perigynia spreading at maturity 13. C. interior. 



32. Perigynia appressed (33). 



33. Perigynia shallowly bidentate 14. C. leptopoda. 



33. Perigynia deeply bidentate 15. C. bolanderi. 



31. Perigynia wing-margined (34). 



34. Bracts conspicuously exceeding the head. 



22. C. ATHROSTACHYA. 



34. Bracts not conspicuously exceeding the head (35). 



35. Perigynia with the beak flattened 21. C. scoparia. 



35. Perigynia with the beak slender and nearly terete (36). 

 36. Perigynia 3 to 3.5 mm. long, plano-convex, ovate. 



19. C. SUBFUSCA. 

 36. Perigynia 3.75 to 7.5 mm. long, flattened (37). 

 37. Perigynia 3.75 to 6 mm. long (38). 

 38. Culms erect; perigynia greenish. 



16. C. FESTIVELLA. 



38. Culms low, ascending or decumbent; perigynia 



blackish 18. C. haydeniana. 



37. Perigynia 6 to 7.5 mm. long (39). 



39. Perigynia finely many-nerved ventrally; scales 



brownish-black or blackish 17. C. ebenea. 



39. Perigynia nerveless ventrally; scales chestnut 

 brown 20. C. wootoni. 



1. Carex douglasii Boott in Hook., Fl. Bor. Amer. 2: 213. 1839. 



Kaibab Plateau and San Francisco Peaks (Coconino County), 

 apparently rare. Manitoba to British Columbia, south to New 

 Mexico, Arizona, and California. 



