S02 



ECOLOGY 



root is removed. The change in the general form of the root 

 system is equally noteworthy, since the large tap root is replaced by a 

 complex of much-branched roots of about equal size (figs. 708, 709). 

 Such a change in form usually occurs when plants {e.g. celery or cab- 

 bage) are transplanted, since the growing tip of the tap root commonly is 

 destroyed in the process. 



Apart from the prevention of overcrowding, transplanting may be of economic 

 advantage, since the shallow and compact root system thus produced is better 



Figs. 713, 714. — A branch of the India-rubber tree (Picus elaslica), illustrating a 

 method of inducing the development of adventitious roots to facilitate artificial propa- 

 gation; an incision is made in the stem, which then is wrapped in wet moss (713): 

 shortly, roots develop at the cut surface (714); note the fall of the sheathing stipule 

 (j) in 714. 



fitted to utilize commercial fertilizers, which, for the most part, remain in the super- 

 ficial soil layers; furthermore, the removal of roots from the soil is facilitated. 

 Nursery trees thrive better than native trees when transplanted, chiefly because a 

 compact root system is developed by frequent transplanting ; if a tap root is allowed 

 to grow to a considerable depth, successful transplanting becomes difficult. Such 

 plants as are used for their roots {e.g. parsnips and carrots) rarely are transplanted, 

 since the process usually destroys the very parts desired ; however, when care is 

 exercised in removing seedlings from the ground, the tap root in some cases con- 



