Rydberg : Rocky Mountain flora 549 



Colorado: Red Cliff, Eagle Co., July 17, 1902, Osterhoiit 

 2706 ; Tennessee Pass, July 28, 1902, Osterhont 2640. 



The first of these specimens was associated with Carduus 

 grisens, Osterhout zjoy (the next number), collected at the same 

 date and locality. C. griseus was collected at Red Cliff in 1906 

 also, Osterhout 3362. C. scopidoriim, the other supposed parent, 

 is rather common throughout the mountains of Colorado. 



Carduus griseus X Parryi 

 Cardjnis araneosus Osterhout, Bull. Torrey Club 32: 612, 1905. 



Osterhout in the original description of Carduus araneosus 

 suggests the relationship with C. Parryi. C. araneosus differs 

 from that species mainly in the less greenish corollas, the stouter 

 and broader spines of the bracts, and the grayish under surface 

 of the leaves. These characters suggest C. griseus, but the in- 

 volucral bracts are decidedly arachnoid-pubescent and the inner 

 bracts are more or less dilated above and erose. The following 

 specimens belong here: 



Colorado: Red Cliff, Eagle Co., June 26, 1900, Osterhout 

 2i6g; and also Aug. 16, 1906, Osterhout 3363; Boreas, July 24, 

 1897, Crandall 2806; without locality, /. Wolf 45 g (Wheeler Exp.). 



The first two specimens were collected at Red Cliff, where 

 also two numbers of C. griseus (see under preceding hybrid) and 

 one of C. Parryi, viz., Osterhout 2^/08, were collected. 



Carduus oreophilus X scopulorum 

 This resembles C. scopulorum in the heads crowded at the ends 

 of the stem, the arachnoid involucres and general habit; but the 

 leaves are broader, with fewer lobes; the involucral bracts are 

 broader at the base, and the flower-cluster not nodding. In 

 these characters it approaches C. oreophilus, but it has less deeply 

 dissected leaves with broader lobes, and the inflorescence is much 

 more arachnoid. 



Colorado: Silver Plume, Aug. 23, 1895, Shear 4g48 and 4g6o. 



Carduus oreophilus also was collected at Silver Plume the same 



day by Shear, no. 32 j8, and also by Rydberg on the following day. 



C. scopulorum is common in the upper part of Clear Creek above 



Silver Plume, In the herbarium of the Garden there is one speci- 



