46 



well in the valleys where the roots can eventually find water, and is 

 probably a little more drought resistant than cottonwood. 



Boxelder is a short-lived tree, and attains no great diameter. The 

 wood takes low rank for fuel and has little other value. A straight 

 trunk seldom forms, because the terminal buds generally die, leaving 

 the lateral ones to continue the upward growth, so that many crooks 

 are produced. Attacks by borers are frequent, and a leaf-aphis often 

 spoils the appearance of the tree. This insect was common on box- 

 elder over a wide range during the season of 1903. Probably it could 

 be checked by spraying if one cared to take sufficient trouble. 



A very respectable street tree is sometimes made of the boxelder by 

 a combination of good care and favorable situation, but its principal 

 use should be for shelterbelts in the valleys. The rate of growth is 

 rapid and the height medium. In a 27-year-old plantation in the 

 Arkansas Valley near Great Bend the trees have an average diameter 

 of about 7 inches and a height of 25 feet. 



While the boxelder does not ordinarily make a permanent tree on 

 the upland, the rate of growth for a few years is likely to be as good 

 as that in the valleys, so no distinction is made in the following table. 



Growth of upland and valley boxelder. 



SILVER MAPLE. 



In congenial situations the silver maple is one of the most rapid- 

 growing trees, but it is not so hardy as either cottonwood or boxelder. 

 and so has a more restricted range. The wood has no especial value, 

 and the chief use of the tree is for ornamental and shelterbelt plant- 

 ing. It is decidedly brittle, and large branches are often broken off 

 in heavy windstorms. Silver maple can be recommended only for 

 valley planting, where the roots will eventually go down to water. 

 In such places it will quickly produce shade and shelter ; the average 

 growth is nearly one-half inch in diameter yearly. 



The measurements which follow were made in lowland or watered 

 situations. 



[Cir. 161.] 



