C 5i 3 



Trunk and Branches, or Stem. Thirdly, the Leaves ; 

 and, fourthly, the Flowers or Seeds. 



The root is that part of the vegetable which least 

 impresses the eye ; but it is absolutely necessary. It 

 attaches the plant to the surface, is its organ of nour- 

 ishment, and the apparatus by which it imbibes foojd 

 from the soil. The roots of plants, in their anatomi- 

 cal division, are very similar to the trunk and 

 branches. The root may indeed be said to be a con- 

 tinuation of the trunk terminating in minute ramifica- 

 tions and filaments, and not in leaves } and by bury- 

 ing the branches of certain trees in the soil, and eleva- 

 ting the roots in the atmospheae, there is, as it were, 

 an inversion of the functions, the roots produce buds 

 and leaves, and the branches shoot out into radical 

 fibres and tubes. This experiment was made by 

 Woodward on the willow, and has been repeated by 

 a number of physiologists. 



When the branch or the root of a tree is cut 

 transversely, it usually exhibits three bodies : the bark, 

 the wood, and the pith ; and these again are individu- 

 ally susceptible of a new division. 



The bark, when perfectly formed, is covered by 

 a thin cuticle or epidermis* which may be easily separ- 

 ated. It is generally composed of a number of laminae 

 or scales, which in old trees are usually in a loose and 

 decaying state. The epidermis is not vascular, and it 

 merely defends the interior parts from injury. In 

 forest trees, and in the larger shrubs, the bodies of 

 which are firm, and of strong texture, it is a part of 

 little importance ; but in the re^ds, the grasses, canes,, 



