156 THE FIRST BOOK OF BOTANY. 



EXERCISE LIX. 

 Parts of a Tree. 



FIG. 264. 



Trunk. 



TRUNK. The main stem of a tree. 

 HEAD. The branching top of a tree. 



Observe the varying lengths of the trunks in the 

 trees about you. Measure the size around their 

 trunks at different heights from the ground. Judge 

 as well as you can at what distance from the ground 

 the lowest limb starts from the trunk. Then test 

 your judgment by measuring. 



If you call the branches that start from the trunk 

 primary, the branches which these put forth may be 

 called secondary branches, and those given off next 

 would be tertiary branches. In observing the heads 

 of trees, fix your attention upon a primary branch, 

 and see if you can find these divisions. Observe 

 whether the tertiary branches bear still other branches. 



