lOO POPtjtAE EEEOKS. 



ing in the west. In tlie east the roots grow mainly 

 near the surface, which makes it difScult to culti- 

 vate newly cleared land for the first few years ; while 

 in Illinois and other parts of the west the roots 

 grow so much deeper, owing to the drier summers, 

 that the cultivation of new land is comparatively 

 easy. 



The depth to which the roots of cultivated plants 

 extend depends also upon the structure of the 

 soil. It is as necessary for most of the roots of a 

 plant to be within the reach of air as it is for the 

 leaves to have light and air. If, then, the air is 

 prevented from entering the soil because of its 

 being too compact, or containing too much moisture, 

 most of the roots will remain near the surface, 

 whereas in deep porous soils they will run deeper. 

 In such soils the roots of clover have been found to 

 the depth of thirteen feet, those of the parsnip 

 twelve to fourteen feet, and those of alfalfa from 

 twenty to thirty feet. 



A few years ago the question of the importance 

 of preserving the fibrous roots in transplanting 

 trees was under discussion. After it became known 

 that roots absorbed food only at or near their 

 extremities the preservation of the smallest fibres 

 in the removal of plants came to be considered a 

 matter of almost essential importance. Further 

 observation, however, showed that these fibres were 



