84 THE ROOT. 



tinues to descend (by the transformation of a portion of the nas- 

 cent tissue) as the growing apex advances ; sometimes, although 

 not usually, inclosing a distinct pith, as the wood of the stem 

 does. The surrounding parenchymatous portion becomes the bark 

 of the root. Increase in diameter takes place in the same way as 

 in the stem. (Chap. IV. Sect. IV.) 



124. We have taken the root of the seedling as an example and 

 epitome of that of the whole herb or tree ; as we rightly may ; for 

 in its whole development the root produces no other parts ; it 

 bears nothing but naked branches, which spring from different 

 portions of the surface of the main root, nearly as this sprung from 

 the radicle, and exactly imitate its growth. They and their rami- 

 fications are mere repetitions of the original descending axis, serv- 

 ing to multiply the amount of absorbing surface. The branches of 

 the root, moreover, shoot forth without apparent order ; or at least 

 in no order like that of the branches of the stem, which have a 

 symmetrical arrangement, dependent, as we shall see, upon the 

 arrangement of the leaves. 



125. To the general statement that roots give birth to no other 

 organs, there is this abnormal, but by no means unusual exception, 

 that of producing buds and therefore sending up leafy branches. 

 Although not naturally furnished with buds, like the stem, yet, 

 under certain circumstances, those of many trees and shrubs, and 

 of several herbs, have the power of producing them abundantly. 

 Thus, when the trunk of a young Apple-tree or Poplar is cut off 

 near the ground, while the roots are vigorous and full of sap, 

 those which spread just beneath the surface produce buds, and 

 give rise to a multitude of young shoots. The roots of the Ma- 

 clura, or Osage Orange, habitually give rise to buds and branches. 

 Such buds are said to be irregular, or adventitious. This power, 

 however, roots share with every part of the vegetable that abounds 

 with parenchyma : even leaves are known to produce adventitious 

 buds. 



. 126. The root has been illustrated from the highest class of 

 PhaBnogamous plants; in which the original root, or downward 

 prolongation of the axis, continues to grow, at least for a consider- 

 able time, and becomes a tap-root, or main trunk, from which 

 branches of larger or smaller size emanate. Often, however, this 

 main root early perishes or ceases to grow, and the branches take 

 its place. In some plants of the highest class (in the Gourd Fam- 



