STEMS 



227 



tendril or even a good leaf in appearance (Fig. 193), is regarded 

 as a branch. Since the significance of a structure is deter- 

 mined by what it can do, it makes little difference what its 



FIG. 195. An Austrian pine. 



origin really is. A tendril does the work of a tendril, whether 

 it is a leaf or a branch that has been " modified." 



Plants differ as to the number of leaves produced by each 

 node. In very many cases only a single leaf is produced by 



