gS UNIVERSITY OF MISSOURI STUDIES [246 



Sub-class 2, DICOTYLEDONES. 



Series i. CHORIPETALAE. 



Order 15. SALICALES. 

 Family 28. SALIC ACE AE Lindl. Willow family. 

 112. POPULTJS 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. 



