ADAPTATION OF CONIFERS 81 



The Black Hills spruce is a very satisfactory tree, with an 

 annual growth of nearly a foot. Its perfect deep green foliage, 

 interspersed with the white inner surface which shows on the 

 new growth, makes a most pleasing picture. It seems to be 

 hardy under all conditions and to have no insect enemies. 



Picea bicolor is very tender and a very slow grower. The 

 leading shoots again and again suffer in the late spring frosts, 

 the trees otherwise appearing to be perfectly healthy. 



With the white pine practically eliminated from planting 

 by the many insect enemies to which it is now subject, except 

 in plantations in which it can be nursed and sprayed with 

 care, the Scotch pine becomes the most rapid grower and the 

 best species to use for covering waste spaces, for windbreaks, 

 or for blocking out inequalities of the landscape. Very variable 

 in habit, some of these trees have a tendency to spread in a 

 most ungainly manner, horizontal branches being thrown out 

 equal in length to the height of young trees, while others 

 assume a pyramidal form or develop a round-topped head and 

 retain a satisfactory appearance for many years. Apparently 

 free from insect enemies, the Scotch pine will grow under any 

 conditions, not minding extreme dryness or even water condi- 

 tions at the roots such as would be fatal to most other pines 

 that can be planted safely in the North. 



Pinus Cemhra is a very slow grower, only about two inches 

 of upward growth being the average of several specimens, the 

 tree being otherwise perfectly healthy. 



Pinus resinosa is one of the most satisfactory pines, being 

 apparently without enemies and having a vigorous growth, 

 not usually averaging more than a foot a year, however, 

 against the two feet or thereabouts of the Scotch pine. This 

 species will not grow when planted in a swamp, as is stated 

 bv some authorities. 



