STUDIES OF SEED-PLANTS 157 



Its branches (secondary roots) grow out sidewise, and the 

 branches grow in various directions, so that they finally result 

 in a complicated root-system with distribution of roots 

 through a large mass of soil. This better fits roots for 

 absorbing from the soil and for anchoring the plant. 



149. Extent of Roots. If one pulls up a plant, such as 

 most common weeds, it becomes evident that if all the little 

 roots were cut and placed end to end, the total extent would 

 be very great. But this would not give an adequate idea 

 of the total extent, for hundreds of small roots are broken 

 in pulling up a plant, as can be proved by comparing a 

 plant pulled from the soil of a pot with one which has been 

 grown without soil. It has been estimated that the total 

 length of roots of a corn plant is over a thousand feet and 

 that a large squash plant has many miles of roots. In 

 ordinary garden soil roots are often found several feet below 

 the surface. In dry regions roots of alfalfa (a kind of clover) 

 are said to go down twenty to thirty feet. However, the great 

 majority of roots of most plants are not far below the surface 

 of the soil, but they extend long distances horizontally. 



In addition to the great length of roots, the root-hairs 

 may increase the absorbing surface so much that a plant with 

 roots of a total length of one foot would equal roots of from 

 twenty to fifty feet without root-hairs. These are estimates 

 made by botanists who have carefully examined roots of 

 various plants. 



The tendency of many roots to extend far from the stem 

 makes transplanting more difficult because so many small 

 roots are necessarily cut off and left in the soil. Gardeners 

 and nurserymen overcome this by transplanting young plants 

 several times, thus forcing the growth of small roots in a 

 cluster near the stem. In order to prepare large trees for 

 moving, it is often necessary to begin several years before 

 and cut off annually a few large roots several feet from the 

 stem so that new branch roots will be grown near the stem 



