14 Characteristics, Structure, Life of Trees 



the base of the daughter branch more and more, while the 



latter itself is also growing in diameter. 



The forester is interested in this 

 method of branch formation, be- 

 cause he knows that, owing to it, 

 every branch or limb which once 

 existed will produce a "knot" in 

 the lumber, although this lumber 

 may be sawed from an apparently 

 branchless bole. As long as the 

 limb remained alive, this will be 

 a "sound" knot; after the limb 

 has died, it will be a "loose" 

 knot (in conifers), or a decayed 

 knot, leaving a blemish or hole in 

 the board. The forester, there- 

 fore, attempts to grow his trees so 

 as to kill out most limbs as early 

 as possible in order to reduce the 

 size and number of knots and thus 

 secure a branchless bole. 



\\'hen, however, a branch is 

 broken or cut off, a dormant bud 

 may develop into a branch. Such 

 dormant buds are connected with 

 the pith by a fine trace of pithy 

 material not large enough to be 

 noted as an imperfection. 



There is an interest in this 

 structural peculiarity which con- 

 cerns the tree-warden. The center 



or pith of the branch or bole, which forms a direct and 



continuous communication through the entire tree from the 



Fig. 6. — Method of formation 

 of a knot. Seven annual 

 layers of wood; a, b, basal 

 parts of a limb which lived 

 four years, then died and 

 broke off near the stem. 

 This leaves a "sound" knot 

 to the left of a, the branch 

 stub to the right forming a 

 " dead " knot soon to be cov- 

 ered by the growing stem. 

 (From Department of Agri- 

 culture, Forestry Bulletin, 

 No. id). 



