FLOWERING PLANTS AND FERNS OF ARIZONA 169 



known to occur in the State, several have been collected in only 

 one locality. More intensive collecting of this genus will, without 

 doubt, extend the range of these species, and will result in the addition 

 of other species to the known flora. 



Key to the species 



1. Spike one; stigmas 3; achenes triangular (2). 



2. Spike entirely staminate or pistillate; plants dioecious. 



28. C. CURATORIUM. 



2. Spike androgynous (3). 



3. Leaf blades flattened, canaliculate, 1.5 to 2 mm. wide toward the base. 



23. C. OREOCHARIS. 



3. Leaf blades acicular, 0.25 to 2 mm. wide toward the base. 



24. C. FILIFOLIA. 



1. Spikes more than one (4). 



4. Stigmas 3; achenes triangular (5). 

 5. Perigynia pubescent (6). 



6. Pistillate spikes many-flowered; achenes with concave sides. 



31. C. LANUGINOSA. 



6. Pistillate spikes few-flowered; achenes with the sides convex above (7). 



7. Plants with no basal spikes 25. C. leucodoxta. 



7. Plants with basal spikes (8) . 



8. Bracts leaf like; culms not strongly filamentose at base. 



26. C. rossii. 

 8. Bracts squamiform when present; culms strongly filamentose at 



base 27. C. geophila. 



5. Perigynia glabrous (9). 



9. Spikes blackish; style jointed to the achene, at length withering (10). 

 10. Lateral spikes linear, the lower ones nodding on long peduncles. 



32. C. BELLA. 



10. Lateral spikes oblong or ovoid (11). 



11. Scales black, with a conspicuous white-hyaline margin. 



33. C. ALBO-NIGRA. 



11. Scales brown or copper-colored 34. C. chalciolepis. 



9. Spikes not blackish; style continuous with the achene, not withering (12). 

 12. Leaves not septate-nodulose; perigvnia nerveless or nearly so. 



37. C. ULTRA. 



12. Leaves septate-nodulose; perigynia strongly ribbed (13). 



13. Perigynia coarsely ribbed 40. C. rostrata. 



13. Perigynia finely and closely ribbed (14). 



14. Perigynia 5 to 7 mm. long, the beak 2 mm. long. 



38. C. hystricixa. 

 14. Perigynia 4 to 5 mm. long, the beak 15 mm. long. 



39. C. THURBERI. 



4. Stigmas 2; achenes lenticular (15). 



15. Lateral spikes peduncled; terminal spike staminate (16). 



16. Perigynia few, pulverulent or golden yellow at maturity (17). 



17. Perigynia whitish-pulverulent at maturity 29. C. hassei. 



17. Perigynia golden yellow or brownish at maturity 30. (\ urea. 



16. Perigynia many, not pulverulent or golden yellow at maturity (18). 



18. Lower sheaths of the flowering culms not breaking and becoming 



filamentose at maturity 35. C. nebraskensis. 



18. Lower sheaths of the flowering culms breaking and becoming fila- 

 mentose at maturity 36. C. senta. 



15. Lateral spikes sessile, short; terminal spikes androgynous or gynaecan- 

 drous, or rarely pistillate or staminate (19). 

 19. Perigynia whitish-puncticulate; spikes gynaecandrous. 



12. C. c \\i:-< ENS. 

 19. Perigynia not whitish-puncticulate (20). 



20. Culms arising singly or few together from long creeping rootstocks; 

 terminal spikes androgynous, or tending to be dioecious (21). 

 21. Perigynia wing-margined, flattened, plano-convex. 



5. C. sic* ATA. 



