136 



FORESTRY 



believe that certain species of trees never produce flowers. The 

 fruits are of various kinds and will repay you for careful study. 

 Trees have definite forms which are characteristic of their 

 species ; some trees are low with round dense heads, as the Nor- 

 way maples, others are tall and open as the elm and plane-tree ; 

 some have a single straight shaft as the pine and hickory, while 

 in others the main trnnk branches in such a manner as to lose 

 its identity in several subordinate branches. 



Fia. 86. — Denuded of forest growth by ruthless cutting and fires. A barren rocky waste 

 ie left, unsuited to other agricultural crops. (U. S. D. A.) 



Tree Foods. — The tree uses the same kind of food and 

 secures it in the same manner as any other plant (Chapter X), 

 and the amount of energy recjuired in securing the raw food, 

 transferring it throughout the plant, and making it into ma- 

 terial of its own is far greater than we can appreciate. Wood is 

 composed primarily of carbon, oxygen and hydrogen. When 

 absolutely dry about one-half its weight is carbon. We have 

 already studied the processes and results obtained in burning 

 M'ood. (Chapter TX.) 



