202 



TREES OF MINNESOTA. 



may. however, be used sparingly to good purpose to brighten 

 up groups of trees and shrubbery which present too gloomy 

 an aspect. It should seldom, if ever, be used as a street tree 

 as masses of it seem to be out of harmony with every good 

 thing in the landscape. In closely settled communities the 

 down on the leaves often becomes filled with soot and gives 

 the tree a dirty appearance. Hard/ everywhere and easily 

 grown from cuttings. 



Populus alba canescens. Silver Poplar. 

 This differs from the above in having leaves broad or 

 nearly circular in general outline, notched but not lobed but 

 like it in that the leaves and young shoots are downy. 



Populus alba bolleana. Bolle Poplar. 

 A form of the White Poplar of the same narrow upright 

 habit of growth as the Lombardy Poplar. 

 Leaves somewhat deeper lobed but with the 

 same cottony covering. It differs from the 

 common White Poplar in that it does not 

 sucker from the root and is more difficult to 

 propagate from cuttings which require to be 

 calloused before planting. It is striking 

 in aspect and should be used sparingly in. 

 ornamental planting. 



Fig. 43. Leaf of 

 Bolle Poplar. One- 

 third natural size. 



Populus laurifolia. (P. certinensis.} 

 Certinensis Poplar. 



Leaves on the old wood or slow growing twigs' are very 

 different from those on vigorous growing shoots. The former 

 are broadly oval with finely serrate margins and on cylindri- 

 cal twigs. The strong shoots are deeply angled or grooved 

 and the foliage on them is wavy in outline. The trees are 

 sometimes confounded with the Cottonwood from which they 

 are very distinct especially in the leaves which are on shorter 

 more rigid petioles. A large tree of rapid growth. 



Distribution. Introduced from Russia. Probably a native 

 of northern Europe and Siberia. 



Propagation. Easily grown from cuttings. 



Properties of wood. Light, soft, easily worked and re- 



