226 



ELEMENTARY STUDIES IN BOTANY 



The nodes not only produce leaves, but if the stem branches, 

 the nodes produce the branches also. It has long been ob- 

 served that a branch arises at a node immediately above a 

 leaf, that is, in the upper angle between leaf and stem, which 

 is called the axil of the leaf (Fig. 192). This usual relation 

 of branches to leaves is merely a relation of position, which is 

 determined by the fact that nodes are constructed to produce 



FIG. 194. The arrangement of leaves: A, spiral or alternate leaves; B, opposite 

 (cyclic) leaves ; C, whorled (cyclic) leaves. After GRAY. 



" lateral members," which in. this case are leaves and 

 branches. Why branches do not usually appear between 

 leaves or below them is a matter of detail that does not con- 

 cern us here. However, it is so usual for a branch to arise 

 from the axil of a leaf that this relative position is often used 

 in determining the nature of a structure. For example, a 

 structure that has a branch in its axil, even if it is a tendril or 

 a thorn, is regarded as a leaf; and conversely, a structure 

 that arises from the axil of a leaf, even if it is a thorn or a 



