142 THE PRINCIPLES OF FLORICULTURE 



the older root-hairs die and new ones are formed. The 

 number of root-hairs is important for they increase the 

 feeding area, just as an abundance of leaf surface increases 

 the area above the soil. It is essential that soil conditions 

 be ideal for the development of large numbers of healthy 

 root-hairs. As these are produced in a restricted area 

 near the tip of the root, older parts of the root system be- 

 come functionless, so far as food absorption is concerned. 

 Long root systems serve simply to hold the plant in posi- 

 tion. 



In addition to absorbing soil water, which holds in 

 solution many elements of plant food, root-hairs also ex- 

 crete carbonic acid. This renders soluble certain minerals 

 in the soil and thus makes them available for food for the 

 plant. 



It is a well-known fact that plants with many fibrous 

 roots are more vigorous and rapid growing than plants 

 with a few long roots. A plant with many root tips has a 

 feeding capacity several times larger than has one with 

 but few long roots. Then again, in plants with a few long 

 roots, it takes more time for food substances to reach the 

 leaves, there to be manufactured into food, and to return 

 again to growing areas in the roots. All cultural treatment 

 should aim to encourage root branching and to have this 

 occur as near the base of the stem as possible. In green- 

 house treatment of plants, this is done by transplanting 

 seedlings when young ; by repotting plants from time to 

 time; by increasing plant food and moisture contents of 

 the soil, and by giving proper soil conditions so that it is 

 well aerated. 



When a seedling is lifted for transplanting, the primary 

 and many of the secondary roots are broken off. Then 

 occurs,, as in an injured stem, a rapid accumulation of food 



