254 UNIVERSITY OF MISSOURI STUDIES [402 



Centaureae (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. Americanuin (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). 



1 189. C. erosum (Rydb.) Cockerell. Nov. comb. [Corduus 

 erosus Rydb.]. Erose-bracted thistle. 



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

 merely erose, otherwise like the preceding. 

 Colorado. 



1 190. C. Coloradense (Rydb.) Cockerell. Nov. comb. [Carduus 

 Coloradensis Rydb.]. Colorado thistle. 



Subalpine valley at Eldora, and frequent along the Arapahoe 

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

 Colorado. 



1 191. C. Plattense (Rydb.) Cockerell. Nov. comb. [Carduus 

 Plattensis Rydb.]. Platte thistle. 



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

 Nebraska to Colorado. 



1 192. C. unduktum (Nutt.) Spreng. [Cniciis undulatus 

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



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

 Michigan to Assiniboia and Montana ; Texas to Utah. 



1 193. 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). 



