AGRICULTURAL BOTANY 



127 



sparkle on the foliage of plants in the sunlight of sum- 

 mer mornings, often mistaken for dew, are usually 

 caused by root pressure. 



Systems of Rootage. - - The roots of some plants, 

 grasses, and grains, for example, grow in a fibrous mat 



\ 



Corn 

 FIG. 53. Systems of Rootage. 



near the surface of the ground. Corn sends its roots 

 out laterally from the plant, and then they turn down- 

 ward to a considerable depth. Clover has a taproot 

 growing downward, with many branches springing off 

 in all directions. 



Plants that send their roots deep into the soil are 

 known as deep feeders, while those whose roots lie near 

 the surface are called shallow feeders. In general, the 

 extreme depth reached by roots is less than their 

 greatest horizontal extent. The depth to which 

 the root grows probably depends largely upon the 



