CHAPTER XI 



THE piire 



139. The Pine Tree. — The pine tree, hke the fem plant, 

 belongs to the asexual generation. We ma}' 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 o-wn weidTit 

 as well as that of the 

 branches and leaves. 

 The trunk grows in 

 length by means of a 

 terminal bud, which 

 includes, besides the 

 growing point of the stem, the ^-ery youngest and smallest 

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

 growing point, and bj- the gro-5\-th of these cells, the trunk is 



"3 



Fig. 64. — A pine tree grown in the open. 

 Photograph by L. S. Chenej-. 



