THISTLE FAMILY 857 



spreading, 4-7 cm. long, 1-2 mm. wide, slightly pannose-tomentose; involucres 

 8-9 mm. long; bracts lanceolate, acutish, scarious-margined, erose, ciliolate, the 

 lower slightly tomentose. C. frigidus concolor A. Nels. Sandy alkaline soil: 

 Wyo. Submont. S. 



19. C. oreophilus A. Nels. Low shrub, 2-4 dm. high; branches grayish 

 with a thin tomentum, yellowish green; leaves erect, linear-filiform, 3-5 cm. 

 long; involucres 8 mm. long; bracts ovate-lanceolate or oblong-lanceolate, 

 abruptly acute. Stony hills: Wyo. Colo. Submont. Jl-O. 



20. C. plattensis Greene. Low undershrub, 2-3 dm. high; branches more 

 or less pannose-tomentose; leaves linear-filiform, tomentose, 3-5 cm. long; bracts 

 in about 3 series, lanceolate, acute, glabrous except the erose-ciliate margins; 

 achenes hirsute-strigose. Plains and hills: Mont. S.D. Colo. Plain Sub- 

 mont. Jl-O. 



21. C. pulcherrimus A. Nels. Shrub, 5-15 dm. high; branches yellowish, 

 minutely lanate; leaves narrowly linear, 5-8 cm. long, 1-2 mm. wide, white- 

 tomentose to nearly glabrate; bracts in 2 or 3 series; linear-lanceolate, ciliate on 

 the margins; achenes softly strigose. Plains: Mont. Colo. Utah Ida. Plain. 

 Au-O. 



22. C. frigidus Greene. Undershrub, 2-6 dm. high; branches white-tomen- 

 tose; leaves narrowly linear, 3-5 cm. long, white-tomentose, rarely glabrate; 

 bracts in 2 or 3 series, lanceolate, the outer acute, the inner obtuse. Plains: 

 Sask. Colo. Utah Alta. Plain Submont. Jl-S. 



23. C. pallidus A. Nels. Small tufted shrub, 2-5 dm. high; branches with 

 close felted tomentum; leaves ascending or spreading, densely tomentose, the 

 lower 4-5 cm. long; heads thyrsoid-paniculate ; bracts ovate-lanceolate, subacute, 

 ciliate on the margins and tomentose on the back. Alkaline flats: n Colo. Wyo. 

 Submont. Au-S. 



24. C. speciosus Nutt. Shrub, 1-2 m. high; branches yellow, sparingly 

 tomentose; leaves numerous, 3-4 cm. long, about 1 mm. wide, white-tomentose; 

 bracts in 3 or 4 series, tomentose, but not ciliate, lanceolate, acute; achenes 

 strigose. B. graveolens A. Gray, mainly. Plains: Ore. Ida. Calif. Son. Jl-S. 



25. C. nauseosus (Pursh.) Britton. Shrub, 5-10 dm. high, permanently 

 white-tomentose, almost cottony; leaves 3-6 cm. long, about 1 mm. wide, tomen- 

 tose, often spreading; bracts lanceolate, acute, more or less tomentose, but not 

 ciliate; achenes hirsute-strigose. B. graveolens albicaulis A. Gray. Hillsides: 

 B.C. Mont. Wyo. Utah Ore. Son. Submont. Je-Au. 



26. C. salicifolius Rydb. Shrub, 3-10 dm. high; branches erect, finely 

 pannose-tomentulose; leaves linear, 3-nerved, 4-6 cm. long, 3-6 mm. wide, 

 minutely tomentulose; heads in a dense corymbiform cyme; involucres 7-8 mm. 

 long; corollas about 1 cm. long; achenes coarsely strigose, angled. B. graveolens 

 lalisquamea A. Gray. Valleys: Utah. Son. Submont. Au-S. 



27. C. stenophyllus (A. Gray) Greene. Low shrub, 1-3 dm. high, much 

 branched; bark white or straw-colored; leaves somewhat involute and twisted, 

 spreading, 2-3 cm. long; bracts in three series, linear, thin, the outer acute, the 

 innermost rounded at the apex; achenes strigose. C. pumilus varus A. Nels. 

 B. Douglasii stenophylla A. Gray. Dry ridges and stony slopes: Nev. Mont. 

 Wyo. Ariz. Submont. Au-S. 



28. C. laricinus Greene. Low shrub, 2-3 dm. high, fastigiately branched; 

 leaves filiform, 1-1.5 cm. long, scabrous-puberulent on the margins; heads few 

 and corymbose; involucre about 5 mm. high; bracts ovate-lanceolate, somewhat 

 keeled, acute with the apex slightly spreading; achenes densely strigose. Valleys: 

 c Utah Ariz. Son. Au-S. 



29. C. pumilus Nutt. Low shrub, 1-3 dm. high; branches glabrous, whit- 

 ish, shining; leaves narrowly linear, 2-4 cm. long, sometimes involute, rarely 

 somewhat twisted; involucres about 5 mm. high; bracts mostly lanceolate, gla- 

 brous, acute or the inner obtuse; achenes sparingly strigose. B. Douglasii pumila 

 A. Gray. Plains and foothills: Mont. Colo. Utah. Ore. Plain Submont. 

 Jl-S. 



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