246 WOODY PLANTS OF MASSACHUSETTS. 



more serious one is the liability of the branches, or even the 

 trunk, when very tall, to be broken by the wind. Its particular 

 office seems to be to act as a screen and as a nurse to other 

 more valuable trees while young. When this office is perform- 

 ed, it may be felled, but is not easily eradicated, on account of 

 the extreme vitality of the roots, which continue for years to 

 throw up suckers. 



In favorable situations, in a moist, rich soil, this tree attains, 

 in a comparatively short time, to a large size. I have not found 

 this tree growing naturally in Massachusetts or elsewhere. It 

 is, however, more frequently planted for shade and ornament 

 than any other tree of the genus. 



Sp. 4. The River Poplar. P. laevigata. Aiton. 



Leaves and a section of a branch figured by Michaux, under the name P. 



Canadensis, Sylva, II, Plate 95. 



The river poplar is a noble tree, rising often to the height of 

 eighty feet or more, with a fine long open head. The trunk is 

 of a light granite gray color, somewhat rough in old trees, with 

 roundish ridges, separated by longitudinal furrows. The young 

 trees and the large branches of old trees are covered with a 

 smooth leather-like bark. The smaller branches are of a light 

 gray ; they are often dependent from the lower limbs. The 

 upper ones go out at a sharp angle, and tend upwards. The 

 recent, vigorous branches and shoots are of a bright green color, 

 like the leaves, with scattered, long, white, lenticellar dots, and 

 strongly angled by three, brown, sharp ridges running down from 

 the base and each side of the leafstalks. Older shoots are of a 

 grayish green, with the ridges longer, more prominent, and of a 

 darker color. The upper branches are conspicuously ridged, 

 with the bark longitudinally cleft, the ridges frequently cracked 

 across. Pith large, five-angled. 



The buds are long, and taper to a long sharp point. The leaf- 

 stalks are nearly as long as the leaves, and gradually and 

 strongly compressed towards the leaf, at the base of which are 

 often situated two or more conspicuous glands. The leaves are 

 very broad ovate or heater-shaped, nearly as wide as long, being 

 from three and a half to four and a half inches wide, and from 



