44 



THE PLANT AND THE SOIL 



which grows only three or four inches high, is known 

 to send its roots into the soil to a depth of seven feet. 

 Alfalfa will send its taproot twenty feet or more into 

 the soil unless prevented by layers of hard soil, rock, 



or water. In the des- 

 ert, where the ground 

 water is very far below 

 the surface, and where 

 the slight rainfall mois- 

 tens the ground to the 

 depth of only a few 

 inches, the roots of 

 desert plants grow only 

 in this shallow layer 

 of soil. 



Kinds of soil. - 

 Plants differ greatly as 

 to the kind of soil in 



CORN ROOT AT LEFT 

 PLANTED IN DEEP- 

 PLOWED SOIL. PLANT 

 AT RIGHT PLANTED 

 IN ORDINARY-PLOWED 

 SOIL 



which they grow well. 



Rye will find plant food and grow on a soil that is too 

 poor for wheat. Clay soils are well adapted to wheat 

 and grass ; while corn grows best in rich, dark loams. 



QUESTIONS 



1. What are the most important functions of roots ? 



2. What plants are called root crops? 



3. What plants have long tap roots ? 



4. What conditions determine the depth to which roots 

 penetrate the ground ? 



