15 



Nelson has accepted it in the New Manual of Rocky Mountain 

 Botany, using Dr. Gray's description. Dr. Rydberg published 

 it as C. Osterhoiitii, Bull. Torrey Club 32: 131; and afterward 

 made it a hybrid of C. griseus X scopiilorum, Bull. Torrey Club 

 37: 548. It is true that there are forms which are intermediate 

 between C. scopnlorum Greene and this plant, but the plant 

 which Dr. Rydberg described and C. scopnlorum are as distinct 

 as are C. Hookerianus Gray and C. eriocephalus Gray as described 

 in the Synopt. Flora N. A.; and if C. Osterhoiitii is distinct from 

 C. Hookerianus I think it should be accepted as a species. 

 Carduus araneosus Osterhout, Bull. Torrey Club 32: 612. 



In the New Manual of Rocky Mountain Botany Prof. Nelson 

 made this a synonym of C. Hookerianus eriocephalus (Gray) 

 A. Nels., and in his list of hybrid thistles Dr. Rydberg classified it 

 as C. griseus X Parryi, Bull. Torrey Club 37: 549. C. Hooker- 

 ianus eriocephalus (Gray) A. Nels., which I have been accustomed 

 to label C. scopulorum Greene, is very leafy, the narrow leaves 

 thickly beset with prickly teeth, the heads in a close cluster, the 

 involucral bracts narrow and long, of nearly the same length, 

 usually long wooly, and no glutinous spot. C. araneosus has 

 broader leaves, the divisions not numerous and comparatively 

 broad, tipped by a weak prickle, the bracts in successive lengths, 

 with a glutinous spot, and arachnoid on the edges. There is 

 scarcely any similarity between the two, and in the natural order 

 they are not closely related. None of the characters which mark 

 C. Parryi or C. griseus appear in C. araneosus to any marked de- 

 gree; there are neither the " lacerate-fimbriate tips" of C. Parryi 

 or the long flat bracts of C. griseus, and neither C. Parryi or C. 

 griseus has a glutinous spot on the bracts. So far as I can see 

 C. araneosus is as good a species as most of our Rocky Mountain 

 thistles. 

 Carduus laterifolius Osterhout, Muhlenbergia i: 141. 



This is another species which has a glutinous spot on the in- 

 volucral bracts. The bracts are in successive lengths and tipped 

 by a slender upright spine. In the typical forms the leaves are 

 broad and little divided; but some other forms which I have 

 placed with it, because they seem nearest to it, have narrower 



