98 UNIVERSITY OF MISSOURI STUDIES [246 



Sub-class 2. DICOTYLEDONES. 



Series i. CHORIPETALAE. 



Order 15. SALICALES. 

 Family 28. SALICACEAE Lindl. Willow family. 



112. POPULUS L. Poplar. Aspen. Cottonwood. 



289. P. tremuloides aurea (Tidestrom) Daniels, Nov. comb.* 

 American aspen. 



Throughout the foothills and mountain region except at the 

 higher elevations, 5800-10000 ft. (Daniels, 314). 



Newfoundland to Hudson Bay and Alaska; New Jersey 

 and Tennessee to Mexico and Lower California. 



290. P. Sargentii Dode. [P. occidentalis (Rydb.) Britton; 

 P. deltoides occidentalis Rydb.]. Western cottonwood. 



Common along streams, ascending Boulder creek as far 

 as Eldora, 5100-8600 ft. (Daniels, 820). Also at Lyons 

 (Rydberg). 



Saskatchewan to Montana; Kansas to Arizona. 



291. P. acuminata Rydb. Black cottonwood. 



A solitary tree near a stream about half way between 

 Boulder and Marshall, 5400 ft. (Daniels, 819). Common in 

 all gulches; there are large trees in Sunshine Canon, 6500 ft. 

 (Ramaley). 



South Dakota to Idaho; New Mexico to Nevada. 



292. P. angustifolia James. Narrow-leaved cottonwood. 

 Along streams and in canons on the mesas and in the 



foothills and mountains, 5400-9000 ft. (Daniels, 52). 



North Dakota to Washington; New Mexico to Cali- 

 fornia. 



293. P. balsamifera L. Balsam poplar. 



Fourth of July mine; Eldora; Allenspark, 8000-10000 ft. 

 (Ramaley). 

 Labrador to Alaska; New England to Colorado. 



*See Appendix A. 



