60 NATURE OF ROOTS 



has been induced in many of these plants by cultivation. If 

 they are left to themselves in a wild condition they will soon 

 revert to an annual growth, i. e., producing seed and perishing 

 during the season. Perennial plants continue to produce new 

 root and stem growths and live on from year to year. 



29. Anchoring and Supporting Roots. Roots also play a very 

 important role in anchoring and supporting the plant. Excellent 

 examples of the supporting roots are seen in the Indian corn 

 where numerous roots spring from the stem a short distance from 

 the ground and reach out on all sides like guy ropes steadying 

 the plant in the ground. Similar devices appear in our elms, 

 maples, and beeches where enlargements of the roots at the base 

 of the trunk rise up like girders bracing the tree against winds. 

 More marked illustrations appear in many tropical plants, as the 

 stilt roots of the mangrove and screw pines, and the buttressing 

 roots of one of the Indian rubber plants (Ficus), etc. In the 

 banyan tree of India the branches have an almost unlimited lateral 

 growth owing to the fact that they are supported by a succession 

 of roots that reach from the branches to the ground. Kerner 

 cites an example of one of these trees with 300 large and 3,000 

 small prop roots. This tree sheltered a village of 100 native 

 huts and an army of 5,000 men. 



30. Binding Action of Roots. The landscape would be con- 

 stantly subject to great change either by erosion or through the 

 action of winds were it not for the solidifying and binding action 

 of roots upon the soil. The difficulty of breaking up the prairies 

 and the turf of abandoned fields or meadows indicates the extent 

 and completeness of the ramifications and interweaving of the 

 roots. Miles of sandy reaches are held from shifting through 

 the restraining action of roots and stems of grasses and other 

 plants. The little town at the end of Cape Cod would have been 

 submerged long ago by the shifting sand dunes had not suitable 

 plants been planted to hold in check the loose sands. Roots 

 not only bind the soil together but the older portion of the root 

 usually possesses the power of contraction. This property re- 

 sults in the pulling down and fixing of the stem in the ground. 

 You must have often wondered how stems and bulbs become so 



