186 THE ANATOMY OF WOODY PLANTS 



lost. The disappearance of the primitive rays from the bundles 

 of the stem is, in fact, a general feature of organization of the true 

 vine type and is as plainly indicated, for example, by the Ranun- 

 culaceae as by the Vitaceae. It is obvious that, as a result of the 

 considerations elucidated above, the typical vine possesses com- 

 pound rays, but that the primitive rays have usually quite dis- 

 appeared. 



FIG. 139. Diagram of the organization of the seedling stem of a northern species 

 of Vitis. 



Very frequently the vine type passes almost imperceptibly into 

 that of herbs, as, for example, in the genus Clematis among the 

 Ranunculaceae and the genus Aristolochia belonging to an order 

 of the same name. It is convenient, however, to take up the ap- 

 pearance of the herbaceous type in an exemplification where it is 

 not linked in any way with the habit or conditions of organization 

 found hi the case of vines. The genus Potentilla will serve admir- 

 ably in the present connection. To reduce the illustrations to the 

 smallest possible compass, and to make the situation at the same 

 time clearer, a diagrammatic mode of representation will be 



