Epidermis 

 ' Cortex 

 Phloem 

 'Xylan 

 a 'Pith 



rk bark 

 Cortex 

 ^Phloem 

 -Xylem 

 -Pith 



Wood ray 

 ambium 



Bark 

 Wood ray 



-Annual ring 

 -Pith 



Pruned 

 branch 



Covered^ 

 branch 



FIG. 55. The structure and growth of a tree 



A, a diagram illustrating the gross anatomy of an oak tree in long section. Note the 

 relation of the annual rings, the junction of the branches with the main trunk, and 

 the covering of pruned branches. J3, transverse sections of the tree shown in A, at 

 three levels. These latter figures are designed to illustrate the early, or primary, 

 structure (a) and the secondary changes (&, c) due to the production of wood and 

 bark by the cork and the fascicular cambiums. Consult the text for a discussion of 



these changes 



