

CHAPTER I. 



ON THE GROWTH AND STRUCTURE OF TREES. 



THE stems of Exogenous* trees may be described as 

 of one uniform structure and mode of increase, and 

 are usually very firm, yielding the most solid and best 

 description of timber, their solidity and strength fitting 

 them admirably for use in carpentry, and for many 

 domestic purposes. 



The most common form of stem is the cylindrical, 

 but it is occasionally found grooved or fluted, and not 

 unfrequently flattened, approximating to an oval ; the 

 cylindrical form being, for most purposes, the best for 

 conversion into beams, joists, boards, &c. 



Botanists speak of the stem as the " ascending axis " 

 of a tree, from its taking an upward direction and giving 

 off branches. In the Elm, these branches take an 

 oblique upward direction ; in the Birch, they are also 

 oblique, slightly pendulous, and flexible ; those of the 

 Willow are somewhat oblique, with the lateral branchlets 

 pendulous and drooping in graceful curves ; in the 



* Exogens are a vegetable class, which augment their woody matter by 

 additions to the outside of that which is first formed ; as long, therefore, 

 as they grow a new layer of wood is added to the outside of the previous 

 growth. The Endogen class i.e., Palms, &c. c. differ from the above, 

 in having their substance formed by successive additions from the inside. 



