FORM AND STRUCTURE 



OF 



Roots, Stems, Leaves, Flowers, and Fruit 



ROOTS. 



The root is that part of the plant axis which does not bear 

 leaves. Normally it grows downward, is fixed in the soil and 

 absorbs nourishment from the soil. True 

 roots produce nothing but root branches 

 and root hairs. 



Roots differ from stems in the following 



particulars. 



cap and Root-hairs. 



They are simpler in internal 

 structure, very irregular in 

 their mode of branching, 

 never directly bear leaves, 

 and their growing point is 

 placed just back of the tip 

 of the root. This tip is 

 covered with a protecting cap called the root- 

 cap and this may push its way without injury 

 to the growing point. The root-hairs are 

 found on the ultimate branches just back of 

 the growing point ; their function is to ab- 

 sorb nutriment from the soil. (Fig. i.) 



When the main root is simple or the 

 branches are small, it is called a tap root. 

 (Fig. 2.) 



When the main root divides very soon and is lost in its 

 branches, the root is called fibrous. 



503 



Fig. 2. — Tap Root. 



