PISUM SATIVUM 



355 



third internode is bisected longitudinally for about 3 cm. The 

 split halves would curve outward if placed in water because of 



^end bu 

 (1-3) 



end bu 

 (l-i) 



end bu 

 (1-5) 



px 

 mx 



end bu 

 (l-i) 



Fig. 179. Transections of axis at various levels to illustrate significant changes in vascular 

 transition. In each figure, the stele and a sector of cortex including one cortical fiber strand 

 are shown. The laterally placed cortical fibrovascular bundles do not appear in the figure. 

 /4, first internode ; B, second internode; C, third internode; D, fourth internode ; w, cortex; 

 CO fi bu, cortical fiber bundle; en, endodermis ; end bu, endarch bundle; ep, epidermis; l-i, 

 l-r, /-3, /-4, 7-5, first, second, third, etc., leaves; mx, metaxylem ; pel, pericycle; ph fib, 

 phloem fibers ; pi, pith ; px, protoxylem ; sti bu, stipular bundle. 



