POPLAR. 273 



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 orna- 

 mental planting. 



Figure 57. Leaf 



One B third natwS Populus laurifolia. (P. Certinensis.} 



size. Certinensis Poplar. 



Leaves on the old wood or slow growing twigs are very dif- 

 ferent from those on vigorous growing shoots. The former are 

 broadly oval, with finely serrate margins and on cylindrical 

 twigs. The strong shoots are deeply angled or grooved, and 

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

 times 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 reported 

 as being valuable for many of the purposes for which pine tim- 

 ber is commonly used. 



Uses. The Certinensis Poplar has been tried largely in this 

 section, and has proved to be a good, quick-growing tree for 

 prairie planting. In some localities, however, it has been in- 

 fested with a borer which has occasionally done much injury, 

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