IS 



TREES AND FLOWERS OF 



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NARROW-LEAVED COTTONWOOD 



Narrow-leaved Cottonwood (Populus angustifoli- 

 us). This tree, although abundant along the streams 

 of the approaches to the Park, is rare in the Park 

 itself. The specimens at Mammoth Hot Springs were 

 planted, as were also the few common or Eastern 

 cottonwoods. The narrow-leaved Cottonwood resem- 

 bles the Eastern variety in size, and general habit of 

 growth, being rather symmetrical when young, but 

 developing irregularly as it becomes older. The bark, 

 smooth on the smaller branches and young trunks, 

 eventually cracks into rough furrows. The distin- 

 guishing feature of course is the narrowness of the 

 leaves, which are frequently no wider than those of 

 some of the broad-leaved willows. 



Aspen (Populus tremuloides) . The aspen, quak- 

 ing-asp, or trembling poplar (it has a number of 

 names) is found all over the Park, but most abundant- 

 ly at the lower levels. It is conspicuous from its 

 greenish-white bark, which is always scarred with 

 black marks, the record of elk and deer browsings. 

 The small, rounded leaves with finely toothed edges 

 tremble on their long, flattened stems in the slightest 

 breeze. The aspen is a "pioneer tree," occupying 

 burned-over areas left by fires, and preceding other 

 species into new lands being invaded by forest growth 



