158 APPLIED BIOLOGY 



before the last long roots are cut at the time of removal to 

 a new location. One firm of tree dealers keeps on its grounds 

 large trees worth several hundred dollars each, which for 

 many years have had their roots cut back in preparation for 

 sale and removal. 



150. Food Storage in Roots. It is a well-known fact 

 that, in addition to the two primary functions of anchoring 

 and absorbing, many roots (turnip, beet, carrot, parsnip, 

 sweet potato, etc.) become thickened and thereby useful as 

 food for man and some animals. However, the primary 

 purpose is not storage for man and animals, but for the plant's 

 use later. Many plants which thus store food in roots use 

 it in the second year for the development of flowers and seeds, 

 and then the plants die. Such are biennials or two-year 

 plants. Other plants which live many years (e.g., rhubarb 

 and asparagus) store food every year during the summer to 

 be used for early growth in the next spring. In fact, when 

 one sees either cultivated or wild plants growing rapidly 

 in very early spring, it is very probable that food stored 

 in the roots furnishes the materials for such rapid growth. 

 This is the explanation of the early flowering of crocuses, 

 daffodils, tulips, hyacinths, snowdrops, spring beauty, and 

 numerous other plants which bloom in very early spring. 



Roots of many species of plants have long been one source 

 of human food ; and in recent years the European practice 

 of feeding roots of turnips, mangels (a kind of beet), ruta 

 bagas (a kind of turnip), and carrots as a part of the food 

 for farm animals has been adopted in many places in America. 



151. Adventitious roots are those given off by the stem 

 or parts of the plant other than roots. The aerial roots of 

 poison ivy, the brace-roots of corn, and parasitic roots of 

 dodder are good examples. Cuttings of stems of willow, 

 poplar, and garden tradescantia placed in bottles with water 

 will soon form adventitious roots. Gardeners start many 

 plants like geranium, coleus, begonia, and numerous other 



