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. Fic. 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 
