854 CARDUACEAE 



Leaves and branches whitc-tomcntose. I 



Leaves mostly erect, the upper reduced, not exceeding the heads. ' 



G. C. Ncwberryi. 

 Leaves arcuate-spreading, the upper longer than the heads. 



7. C. Howardii. , 



Oiiter bracts short, neither produced nor foliaceous. j 



Heads 5-8 mm. high; bracts thin, glabrous. | 



Leaves 2-3 cm. long, over 1 mm. wide, light green. < 



8. C. Greenei. \ 

 Leaves 1-2 cm. long, less than 1 mm. wide, dark green. ] 



9. C. niifolius. J 

 Heads about 1 cm. long; bracts thicker. j 



Leaves less than 1 mm. wide: bracts glabrous. 10. C. albidux. ' 



Leaves 1 mm. broad or broader; bracts arachnoid-ciliate. ^ 



Leaves 1-2 cm. long; involucre lanate as well as arachnoid. 



11. C. collinus. 

 Leaves 3-6 cm. long; involucre somewhat viscid, merely arachnoid- 

 ciliate on the margin. 12. C. wyomingensis. 

 Bracts not acuminate. 



Bracts 6-7 in each vertical row. 13. C. formosus. 



Bracts 3-5 in each vertical row. 



Achenes pubescent; bracts acute or obtuse. 



Branches, at least when young more or less whitened with a pannose tomen- 

 tum; style-appendages longer than the stigmatic portion; corolla 7-12 

 mm. long. 

 Bracts and mature leaves perfectly glabroas. 



Bracts ovate, or the outer triangiilar; involucre about half as long as 



the flowers. 14. C. virenx. 



Bracts lanceolate to linear; involucre more than half as long as the 

 flowers. 

 Leaves nearly erect or strongly ascending, straight, 1-2 mm. wide. 



15. C. graveolens. 

 Leaves scarcely 1 mm. wide. 



Leaves spreading or reflexed, more or less falcate: lobes of the- 



corollas lanceolate, mostly acute. 10. C. patens. 



Leaves erect, about 0.5 mm. wide; lobes of the corolla ovate, 

 obtuse, about 0.5 mm. long, erect in age. 



17. C. pinifolius. 

 Bracts erose-ciliate on the margin, or tomentose, or both. 



Inflorescence elongate-thyrsoid. 18. C. concolor. 



Inflorescence corj-mbiform, flat or round-topped. 



Bracts lanceolate, acute; leaves less than 2.5 mm. wide. 

 Bracts more or less erose-ciliate on the tliin margins. 



Mature leaves glabrous or nearly so, about 1 mm. wide, erect. 



19. C. oreophilus. 

 Mature leaves more or less densely white-tomentose; bracts 



lanceolate. 

 Leaves 1 mm. wide or less, spreading. 



20. C. plattensis. 

 Leaves 1-2.5 mm. wide. 



Bracts narrow, linear-lanceolate, strongly carinate, 

 almost glabrous, except the erose-ciliate margins. 



21. C. pulcherrimus. 

 Bracts usually broader, more or less deiasely tomentose 



and viscid as well as ciliate. 

 Stems equally leafy tliroughout; leaves all alike, 

 strongly ascending; bracts strongly carinate. 



22. C. frigidus. 

 Stems more leafy towards the ends; upper leaves 



much shorter; bracts slightlv carinate. 



23. C. palUdus. 

 Bracts not at all ciliate on the thicker margin, but white-tomen- 

 tose on tlie back. 



Bracts scarcel.v carinate; older branches not densely and 



tliickly woolly. 24. C. spcciosus. 



Bracts strongly carinate; older branches densely and thickly 

 woolly. 25. C. nnuseosus. 



Bracts elliptical, nearly glabrous, the tliuiner ones obtuse: leaves 

 3-4 mm. wide. 26. C. salicifnlius. 



Branches without tomentum; style-appendages shorter than the stigmatic por- 

 tion; coroUa 5-7 mm. long. 

 Leaves and the wliite or straw-colored stem glabrous or nearly so, except i 

 the hispidulous-cUiate margins of tlie former. 

 Leaves narrowly luiear, 2 mm. wide or less. 



Bracts neither strongly carinate nor with conspicuous green tips. 

 Leaves less than 1 mm. wide, 1-nerved. 



Bracts linear, tlie innermost rovmded at the apex. 



27. C. stenophijllus. 

 Bracts ovate-lanceolate, acute. 28. C. lariciniis. 



Leaves 1-2 mm. wide, 3-nerved; bracts lanceolate. 



29. C. pumilus. 



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