CARDUACEAE. 
341 
Leaves 2-3 cm. long, over 1 mm. wide, light green. 
7. C. Greenei. 
Leaves 1-2 cm. long, less than 1 mm. wide, dark green. 
8. C. dlifolhis. 
Heads about 1 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 tne 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. 11. 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 1 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. condnis. 
Bracts erose-ciliate on the margin, or tomentose, or both. 
Leaves 1 mm. or less, spreading. 16. C. plattensis. 
Leaves 1-2.5 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. frigidns. 
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. 
Leaves 1-2.5 mm. wide, usually twisted. 
Achenes glabrous; bracts rounded at the apex. 
23. C. lanceolatns. 
24. C. puberulus. 
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. 
