90 



STRUCTURAL BOTANY. 



[76, 77. 



which supports their branching tops and withstands 

 the assaults of the wind by means of the great firm- 

 ness and strength of the woody or ligneous tissue with 

 which it abounds. The trunk is usually seen simple 

 and columnar below, for a certain space, then variously 

 dividing itself into branches. Here it is cylindrical, 

 straight, and erect, as in the Forest Pine ; prismatic 

 often, as in the Gum-tree ; gnarled and curved, as in 

 the Oak ; or inclined far over its base, as in the Syca- 

 more. 



S B E 



256, 5, Spruce. B, Beech. E, Elm ; to illustrate excurrent and deliquescent axis. 



226. In dividing itself into branches, we observe 

 two general modes, with their numerous variations, 

 strikingly characterizing the tree forms. In the one, 

 named by Lindley the EXCURRENT, the trunk, from the 

 superior vigor of its terminal bud, takes precedence of 



