The Trees of Vermont 51 



en in the above, key, will enable one to distinguish the native black willow 

 from the introduced species. Nor will it be found difficult to distinguish 

 typical trees of the white willow from typical trees of the crack willow by 

 the characters given in this key. As a matter of fact, however, there are 

 numerous varieties and hybrids between these two willows which it is 

 impossible to classify under either name. 



The white willow is large and graceful, and this, coupled with the ease 

 of starting it from cuttings, makes it a deservedly popular shade tree. 



* 

 CRACK WILLOW. Scdix fvagilis Linn. 



Most of the statements made in the discussion of the white willow apply 

 to this species also. A distinctive characteristic of the twigs, aside from 

 their color, is that they are very brittle, especially near the base, whence 

 the name. 



THE POPLARS. 



The poplars belong to the willow family and resemble the willows 

 especially in flower and fruit characters. The nodding, worm-like, 

 staminate and pistillate catkins are borne upon different trees and, opening 

 before the leaves, are conspicuous in early spring. The poplars are quite 

 widely distributed, extending from the Arctic circle to Mexico and from 

 the Atlantic to the Pacific. 



The wood of poplars is very soft and light and especially liable to 

 warp, but is cheap and useful for making toys, boxes and smaller furniture. 

 Much of it now goes to the pulp mills. 



Leaves coarsely and bluntly toothed or scalloped. 



Leaves roundish, especially at the base Largetooth Aspen 



Leaves triangular, with straight or truncate base Cottonwood 



Leaves finely toothed. 



Leaves small, nearly as broad as long, petioles much flattened American Aspen 



Leaves larger usually much longer than broad, petioles not flattened. Balsam Poplar 



Introduced species.— In addition to these native poplars two European 

 species are very commonly planted, the Lombardy poplar, (P. nigra 

 Italica) recognized by its tall spire-like form, and the white poplar, (P. 

 alba) easily distinguished by its leaves, green above and very white-cottony 

 beneath. 



ASPEN (AMERICAN OR QUAKING ASPEN ). PopuluS trcmuloideS Michx. 



The most careless observer cannot have failed to notice the leaves of the 

 aspen continually trembling on the quietest summer day. This tremulous- 

 ness has, indeed, given name to the species. The reason for it, as may 

 readily be seen by examination of any leaf, lies in the decidedly flattened 



