THE NEEDS OF PLANT ROOTS 31 



into the soil in all directions. Roots are of many kinds 

 and shapes, from the fibrous ones of the grasses to the long, 

 slender taproot of alfalfa and the heavy, thickened root of 

 the mangel and sugar beet. 



28. How the Root Grows. All roots are alike in that they 

 end in a rather hard, pointed portion about a quarter of an 

 inch long called the root cap. It is by means of this root cap 

 that the young, tender root forces its way between the soil 

 particles. The lengthening of the root takes place just back 

 of the root cap rather than along the entire length, so that 

 the root is enabled to find its way around obstacles, such as 

 pebbles and other impervious objects in the soil. It is 

 evident that a fine, mellow soil is important for the free 

 growth of roots, as it is more easily penetrated by them. 

 Just back of the root cap are small rootlets or root hairs, 

 which are the feeding roots of the plant. These root hairs 

 come into very close contact with the soil particles, as will 

 be found when a plant is dug up and the earth is washed from 

 the roots carefully. It will be very difficult to remove all 

 the fine particles of soil from these root hairs, so closely do 

 they cling. These root hairs will be found only along a few 

 inches of the growing portion of the root just behind the root 

 cap. 



29. Roots Take in Water. It has already been stated 

 that the leaves of plants give off water by transpiration. 

 Naturally, there must be some source of supply from which 

 this water is drawn and some means of conveying it to the 

 leaves. The source of supply is the moisture in the soil; 

 it is taken in through the roots, whence it passes through the 

 stem to the leaves. The inner bark of the root and the S!<MU 

 is made up largely of hollow cells placed end to end, which 

 make a ready means of passage for this water, or sap, as it is 

 ordinarily called after it is taken in by the plant. A shortage 



