CHAPTER XI 



THE PINE 



139. The Pine Tree. The pine tree, like the fern plant, 

 belongs to the asexual generation. We may expect, therefore, 

 to find that in some 

 way the tree pro- 

 duces spores. First, 

 however, we shall 

 study the vegetative 

 parts of the tree, 

 namely, the stem 

 (trunk) and its 

 branches, the leaves, 

 and the roots. The 

 trunk, because it con- 

 tains many thick- 

 walled cells, can 

 stand erect and sup- 

 port its own weight 

 as well as that of the 

 branches and leaves. 

 The trunk grows in 



length by means of a 



. FIG. 64. A pine tree grown in the open, 



terminal bud, which Photograph by L. S. Cheney, 



includes, besides the 



growing point of the stem, the very youngest and smallest 



branches and leaves. By the formation of new cells at the 



growing point, and by the growth of these cells, the trunk is 



"3 



