408 THE ANATOMY OF WOODY PLANTS 



the herbaceous dicotyledons, on the contrary, we find the origin 

 of herbaceous texture closely associated with special modifications 

 in the organization of the secondary cylinder, and this involves 

 a high degree of specialization on the part of the plants in which 

 it is manifested. The local transformation of the tissues of the 

 woody cylinder, in relation to improved storage in proximity to 

 the leaf trace, had its early expression in the phenomenon of 

 aggregation of rays in proximity to this in its course through the 

 woody cylinder. The phenomenon of aggregation is succeeded 

 in turn by that of compounding, the direct consequence of the 

 facility with which the longitudinal elements of the xylem become 

 transformed into storage elements in the case of the dicotyledons. 

 The final result achieved in the compound ray is the wedding of 

 longitudinal and radial parenchyma in the complex, which becomes 

 of such marked significance in the herbaceous dicotyledons. 



