254 UNIVERSITY OF MISSOURI STUDIES [402 



Centaur eae (Rydb.) Cockerell. Nov. comb.]. KNAPWEED 

 THISTLE. 



Common in the foothills and mountains, 6000-10000 ft. 

 (Daniels, 442). Also mountains between Sunshine and Ward 

 (Rydberg). 

 WYOMING to COLORADO. 



ii88a. C. Americamun (Gray), Daniels. C. griseum (Rydb.) 



Cockerell. 

 Ward (Rydberg). 



1188^. C. acaulescens (Gray) Daniels; Nov. comb. C. 



Americanum (Gray) Daniels. 

 Plains and foothills near Boulder (Rydberg). 



1189. C. erosum (Rydb.) Cockerell. Nov. comb. [Carduus 

 erosus Rydb.] . EROSE-BRACTED THISTLE. 



Boulder Canon, 7000-7500 ft. (Daniels, 1032). Bracts 

 merely erose, otherwise like the preceding. 

 COLORADO. 



1190. C. Coloradense (Rydb.) Cockerell. Nov. comb. [Carduus 

 Color adensis Rydb.]. COLORADO THISTLE. 



Subalpine valley at Eldora, and frequent along the Arapahoe 

 Trail, 8600-10000 ft. (Daniels, 855). 

 COLORADO. 



1191. C. Plattense (Rydb.) Cockerell. Nov. comb. [Carduus 

 Plattensis Rydb.]. PLATTE THISTLE. 



Plains about Boulder, 5100-6000 ft. (Daniels, 63). 

 NEBRASKA to COLORADO. 



1192. C. undulatum (Nutt.) Spreng. [Cnicus undulatus 

 (Nutt.) Gray; Carduus undulatus Nutt.]. 



Common on the plains, 5100-6000 ft. (Daniels, 673). 

 MICHIGAN to ASSINIBOIA and MONTANA; TEXAS to UTAH. 



1193. C. megacephalum (Nutt.) Cockerell. Nov. comb. [Cni- 

 cus undulatus megacephalus (Nutt.) Gray; Carduus mega- 

 cephalus Nutt.] . LARGE-HEADED THISTLE. 



Plains about Boulder, 5100-6000 ft. (Daniels, 986). 



