ROOTS 



41 



soil-roots, and grows rapidly on the strength of the sup- 

 plies of ready-made sap which it obtains from the host. 



52. Forms of Roots The primary root is that which 



proceeds like a downward prolongation directly from the 

 lower end of the hypocotyl. In many cases the mature root- 

 system of the plant contains one main root much larger 

 than any of its branches. This is called a taproot (Fig. 17). 



Such a root, if much thickened, would assume the form 



FIG. 17. A Taproot. FIG. 18. Fibrous Roots. FIG. 19. Fascicled Roots. 



shown in the carrot, parsnip, beet, turnip, salsify, or radish, 

 and is called a fleshy root. Some plants produce multiple 

 primary roots, that is, a cluster proceeding from the lower 

 end of the hypocotyl at the outset. If such roots become 

 thickened, like those of the sweet potato and the dahlia 

 (Fig. 19), they are known as fascicled roots. 



Roots of grasses, etc., are thread-like, and known as 

 fibrous roots (Fig. 18). 



53. General Structure of Roots The structure of the 



very young root can be partially made out by examining 



