Handbook of Teees of the Nortjieen States and Canada. 05 



This stately tree is the largest representa- 

 I tive of its genus, sometimes surpassing 100 ft. 

 in height, with trunk 6—8 ft. in diameter. It 

 develops a full wide or rounded top with few 

 massive branches, and these often spreading far 

 out extend their drooping branches and shining 

 dark green leaves over a very wide area. It 

 is confined to the rich moist soil of river bot- 

 toms and the banks of streams and along those 

 of the mid-continental regions it is the largest 

 and most characteristic tree. East of the 

 Alleghany Moxuitains it is less abundant and 

 a smaller tree; still here and there con- 

 spicuously large trees are found. 



The wood is light and soft, a cubic foot when 

 absolutely dry weighing 24.24 lbs., and is used 

 for paper pulp, in the manufacture of lumber 

 for packing cases and for fuel. Owing to ten- 

 dency to warp and difficulty in seasoning it is 

 little valued tor lumber. In early days, how- 

 ever, before railroads crossed the western 

 plains the pioneer settlers found in the Cotton- 

 wood trunks material for building purposes 

 from the rough stockade to the houses an 1 

 buildings of their first villages. 2 



Leaves broadly deltoid-ovate, 3-7 in. long, usually 

 abruptly acuminate at apex, truncate or slightly 

 cordate at base, crenate-serrate, entire at base, at 

 first gummy witb fragrant exudation but Anally 

 lustrous dark green above, paler beneath ; petioles 

 long, slender, and laterally compressed. Flowers 

 (April-May): aments short-stalked; staminate 

 stout and densely flowered, 3-5 in. long ; stamens 

 numerous : pistillate at first smaller but elongat- 

 ing as fruit ripens ; scales glabrous, laciniate. 

 Fruit with ovoid 2-4-valved capsules, which liber- 

 ates in May their crowded contents of small light 

 brown seeds with cottony coma. 



P. deltoides occide iitalls Rydb. is a western form 

 ranging from Sask. to New Mexico with leaves 

 broader at base, longer-acuminate and more 

 coarsely toothed with young branches shining, 

 light yellow. 2 



1. Syn. Popuhts monilifera Ait. 



-2. A. W., II, 48. 



3. For genus see pp. 426-427. 



