THE ROOT 



145 



We may now turn our attention to the particular features of 

 organization presented by the younger and older root in a conifer. 

 In the early stage of development presented in Fig. 102 the fibro- 

 vascular region is sharply separated from the rest of the transverse 



FIG. 102. Transverse section of a young root of the American larch 



section by a well-marked endodermis. Within this layer lies a 

 broad zone, the pericycle, which abuts upon the primary phloem. 

 Inside of the primary phloem lie two bands represented as double 

 rows of cells with protoplasmic contents. This is the cambium, 

 which provides the elements of the secondary xylem and phloem, 

 neither of which can be said as yet to have come into existence. In 



