14 AUSTRALIAN BOTANY. 



epidermis around the outside in the first, which increase 

 the diameter successively, while in the latter the increase 

 of cells takes place interiorly, narrowing the hollow of the 

 stem, but not changing the original dimensions laterally. 

 This is the reason why the terms Exogens (outward growers) 

 and Endogens (inward growers) are applied to these two 

 great divisions. 



Having now learned something about the internal 

 structure of plants, and thereby gained some insight into 

 their economy, the technical description of the various 

 parts of plants, with their varied modification of external 

 form, will prove more intelligible and interesting, especially 

 if we turn into the fields and examine for ourselves, when 

 we will find that the more we become familiar with the 

 actual appearance of the various forms, the more delight 

 we will find, while the horrors of ' sesquipedalian ' terms 

 vanish before we are aware of the fact. 



LESSON III. 



ROOTS. 



The Roots of plants, though not so diversified as the upper 

 growth, have many important differences in shape. The 

 broad signification of the word Root is that portion of the 

 plant which grows beneath the ground, holding firmly in 

 the soil, and absorbing or taking up nourishment for its 

 sustenance. 



There are exceptions to this, as to many other botanical 

 rules. The ivy, for instance, as shown in Plate I. fig. 3, throws 



