138 



ROOTS 



In anchor ing the shoot most soil roots perforin an important 

 function, except in those plants with stems prostrate on the ground 

 or climbing supports. In plants with upright stems, as in trees, 

 the strains due to winds and gravity when the plant is bearing 

 foliage and fruit is often enormous. However, the root system 

 is usually able to hold the plant in place, although the strains 

 may break off })ranches or even the main stem. It is by spread- 

 ing laterally and profusely branching, that roots become so firmly 

 attached to large masses of soil that they can endure enormous 

 strains. 



In addition to anchoring the plant and furnishing it water and 

 mineral matter, in many plants the roots function as storage or- 

 gans, in which some of the food made by the shoot each year is 

 stored for use in the development 

 of new shoots each succeeding year. 

 This function is especially obvious 

 in many plants which die down in 

 the fall and grow up again in the 

 spring. 



Thus the root depends upon the 

 shoot for food while the shoot de- 

 pends upon the root: (1) for water 

 and mineral matter; (2) for an- 

 chorage; and (3) often as a storage 

 organ. 



Types of Root Systems. — There 

 are various irregularities among 

 root systems, due to the altera- 

 tions which a root system must 

 make in adjusting itself to obstruc- 

 tions and the uneven distribution 

 of water and mineral matter in the 

 soil. For this reason root systems 

 are less symmetrical than shoots. 

 However, despite these irregulari- 

 ties there are some inherent differ- 

 ences that are so regular as to be typical of certain plants. 



In the Corn, Wheat, Oats, and Grasses in general, there is the 

 type of root system, known as the fibrous root system, in which 

 there are no dominant main roots, but all roots are small and with 



Fig. 122. —The fibrous roots 

 of Corn. 



