NATURE OF PLANTS 



93 



a leaf falls off, the ends of these vascular bundles can be easily 

 seen in the leaf scar (Fig. 28, A) but owing to their minuteness 

 it is not an easy matter to trace them through the stem to the 

 point where they join on to the bundles of the stem. In the 

 branch, however, owing to its size and woody character, the 

 union with the stem is very manifest. Fig. 64 shows several 



Fig. 63. Diagram of the tip of a stem as seen in longitudinal section: 

 a, formative region corresponding to the part shown in Fig. 61; /, b, leaves 

 and branches in various stages of_development; v, vascular bundles; c, cortex; 

 p, pith. 



very small branches that continued to keep pace for one or more 

 years with the growth of the stem, but eventually they were 

 killed by the overhanging branches and in time became over- 

 grown with the annual layers of xylem. If the branch is favor- 



