STEMS 



43 



it has developed into a great variety of forms or habits. 

 In some trees, as the pines and their allies, the main stem 

 continues as a central shaft to the top, the branches spread- 



FIG. 42. An Austrian pine. 



ing horizontally from it (Fig. 42); while in other trees, as 

 the oak and the elm (Figs. 43 and 44), the main stem 

 soon divides into large branches. In the former case the 



