Water and the Plant 



77 



long as the plant lives 

 and is active, the root 

 system continues to 

 branch and send out a 

 mass of young rootlets. 

 When their limit of depth 

 and breadth is reached, 

 branches continue to fill 

 in the space between 

 with a network of the 

 fine roots. 



A short distance be- 

 hind the tip of a rootlet 

 there is a growth some- 

 what resembling cotton 

 fibers. If we look at this 

 with a reading glass or 

 a simple pocket mag- 

 nifying glass, we find 

 that this is composed of 

 delicate hair-like out- 

 growths from the root 

 itself. Each of these 

 root hairs is a slender 

 tube that has grown out - drain off the water from them - 

 from the side of a cell. It is a rod-shaped structure, 

 closed like a finger of a glove at its outer end, and by 

 its growth it thrusts itself in among the soil particles 

 and absorbs water and mineral compounds in solution. 

 In this way the absorbing surface of the rootlet is enor- 

 mously greater than if no root hairs were developed. 



FIG. 46. Young radish seedling with soil 

 clinging to root hairs. The root hairs 

 penetrate among the soil particles and 



