82 THE ELEMENTS OF VEGETABLE HISTOLOGY 



PLATE 31. A. Completion of Fibro vascular Bundles. 



F. Completed fibro vascular bundle. 1. Xylem elements. 2. Cambium. 

 3. Phloem elements. 



B. Arrangement of Secondary Tissues in Roots and Stems. 



1. Periderm (bork). 2. Phellogen. 3. Phelloderm (bark). 4. Phloem ele- 

 ments. 5. Cambium. 6. Xylem elements. 7. Medullary rays. 



