Rydberg : Studies on the Rocky Mountain Flora 507 



This species is nearest related to E. Montancnsis, from which it 

 differs in the narrower, blue or purple rays and longer and less 

 pubescent leaves. It grows at an altitude of 2000-2700 m. 



Wyoming : Little Goose Creek, 1899, F. Tweedy, 2003 (type) ; 

 Headwaters of Clear Creek and Crazy Woman River, 1900, joio. 



v Carduus Centaureae sp. nov. 



(?) Cnicus carlinoides var. Americanns A. Gray, Proc. Am. 

 Acad. 10: 48. 1874. Not Cirshtm acaide var. Americanus 

 A. Gray. 1863. 



(?) Cnicus Atnericanus A. Gray, Proc. Am. Acad. 19 : 56. 



Biennial or perennial. Stem rather slender, 6-10 cm. high, 

 striate, often tinged with red, slightly floccose when young : basal 

 leaves about 2 dm. long, thin-petioled, deeply pinnatifid to near 

 the midrib, above light green, sparingly floccose when young, 



glabrate in age, beneath more or less permanently grayish-to- 



mentose ; lobes lanceolate or triangular, 2-4 cm. long, more or 

 less toothed and tipped with weak spines, 1-3 mm. long ; lower 

 stem-leaves similar but petiole more winged, dilated at the base 

 and short decurrent ; the upper sessile and clasping with an 

 auricled base ; the uppermost lanceolate and undivided : heads 

 2-2.5 cm. high and 1.5-2 cm. in diameter : outer bracts narrowly 

 lanceolate, yellowish, often with darker center, fimbriate on the 

 margin and tipped with a flat weak spine 1-2 mm. long: the 

 inner with dilated deltoid scarious fimbriate tips which are merely 

 acuminate : flowers ochroleucous. 



This species may be the Cnicus Americanus A. Gray or Carduus 

 Atnericanus Greene, but the name Americanus is preoccupied. The 

 species is, however, not nearest related to C. Parryi, where Dr. 

 Gray placed it ; but to C leiocephalus and C canovirens, from 

 which it differs in the less spinose, more dilated and fimbriate 

 bracts. A seedling of apparently this species was collected by 

 Cowen and it has long oblanceolate 3-4 dm. long, undivided 

 leaves. It grows at an altitude of 2200-2600 m. 



Colorado : Laramie County, 1895,/. H. Cowen (type) ; 4-mile 

 Hill, Routt County, 1896, C F. Baker; Penn's Gulch, 1865, 



Lett erf nan, 78. 



4 Carduus erosus sp. nov. 



Biennial. Stem stout, about 7 dm. high, angled and striate, 

 often red, loosely floccose when young : lower leaves about 2 dm. 

 lon g, rather thin, green and slightly floccose above when young : 



