64 



COLLEGE BOTANY 



stems from roots is much less frequent than the production of 

 roots from the stems (page 56). Some climbing plants, such 

 as the trumpet creeper and the poison ivy, produce roots which 

 serve as holdfasts and enable them to cling to trees, walls and 

 other objects. The climbing roots should not be confused with 

 stems which also serve this function (page 62). 



Structure of Roots. The root consists of the same kinds of 



FIG. 41. FIG. 42. 



Fia. 41. Diagrammatic longitudinal section of root tip showing: (a) axis cylinder; (c) cortex; 



(e) epidermis; (x) root-cap. 

 FIG. 42. Cross-section of root tip showing cellular structure and root-hairs. 



tissues as are found in the stem, but the arrangement is somewhat 

 different. There are four well-defined regions : the axis cylin^ 

 der in the center, which is surrounded by the endodermis; then 

 a zone known as the cortex, and finally the outside covering or 

 epidermis. On the tip of the root is the cap (Figs. 41 and 42), 

 a loose but well-defined mass of cells forming a protective cover- 

 ing over the growing point* 



