CARDUACEAE. 341 



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



7. C. Greenei. 

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



8. C. filifolius. 

 Heads about i cm. long ; bracts thicker, arachnoid-ciliate. 



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



9. C. collinus. 



Leaves 3-4 cm. long; involucres somewhat viscid, merely arachnoid- 

 ciliate on the margin. 10. C. wyomingensis. 



Bracts not acuminate. 



Achenes pubescent ; bracts acute or obtuse. 



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

 mentum ; style-appendages longer than the stigmatic portion ; corolla 

 7-10 mm. long. 

 Bracts and mature leaves perfectly glabrous. 



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



the flowers. n. C. virens. 



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



flowers. 



Lobes of the corollas lanceolate, mostly acute, in age spreading. 

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



12. C, graveolens. 

 Leaves spreading or reflexed, more or less falcate, about i mm. wide. 



13. C. patens. 

 Lobes of the corolla ovate, obtuse, about 0.5 mm. long, erect in age. 



Leaves about 0.5 mm. wide. 14. C. pinifolius. 



Leaves about 2 mm. wide. 15. C. confinis. 



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



Leaves i mm. or less, spreading. 16. C. plattensis. 



Leaves 12.5 mm. wide. 



Bracts narrow, linear-lanceolate, strongly carinate, almost glabrous, 



except the erose-ciliate margins. 17. C. pulcherrimus. 



Bracts usually broader, more or less densely tomentose and viscid 



as well as ciliate. 18. C. frigidus. 



Branches green, without tomentum ; style-appendages shorter than the stig- 

 matic portion ; corolla 5-7 mm. long. 



Leaves and stem glabrous or nearly so, except the hispidulous-ciliate mar- 

 gins of the former. 

 Leaves narrowly linear, 1-2 mm. wide, strongly twisted. 



19. C. elegans. 

 Leaves linear to lance-linear or oblanceolate, 2-8 mm. wide, not twisted. 



Bracts linear, oblong, or lanceolate. 



Bracts at least the outer ones with thick green tips. 



20. C. linifolius. 

 Bracts comparatively thin, not green-tipped. 21. C\ serrulatus. 



Bracts ovate, oval or the inner broadly elliptic. 



22. C. latifolius. 

 Leaves and stem decidedly puberulent. 



Leaves 3-6 mm. wide, rarely twisted. 23. C. lanceolatus. 



Leaves 1-2.5 mm - wide, usually twisted. 24. C. puberulus. 



Achenes glabrous ; bracts rounded at the apex. 25. C. Vaseyi. 



1. Chrysothamnus depressus Nutt. (Bigelovia depressa A. Gray) Plains 

 of Utah, Colo, and N. M. Alt. 4000-8000 ft. Gunnison ; Squaw Creek, above 

 Cimarron. 



2. Chrysothamnus pulchellus (A. Gray) Greene. (Bigelovia pulchella A. 

 Gray) On dry hills from Colo, and Utah to Tex. and N. M. ; also in Mex. 

 Exact locality not given. 



