TRITICUM 



163 



bundle. In this manner, the common bundle is formed which 

 extends to the cotyledonary plate where it is united with the bundle 

 from the midrib of the second leaf. (3) The remaining four lateral 

 bundles of the second leaf and two lateral bundles of the third 

 leaf; and (4) the vascular elements of the seminal roots which 

 anastomose with the bundles of the second leaf and are connected 



Fig. 71. A transection of the second internode of young whleat plant. 



indirectly with the lateral bundles of the third leaf. (Figs. 70 

 and 71.) 



The second internode, which extends from the point of diver- 

 gence of the coleoptile to the first foliage leaf above, is less transi- 

 tional in character than the first internode. It resembles the 

 higher internodes except that the bundles are not as clearly defined, 

 and there are some strands in which the differentiation of the 

 xylem is intermediate between the exarch and the endarch arrange- 

 ment. (Fig. 72..) 



The Anatomy of the Stem. — In most wheats, the culm is sub- 

 terete, hollow in the internodal regions and solid at the constricted 



