THE STEM PROPER 



circumference of the stem ; how many years has the tree 

 lived since the knot was formed ? Does this agree with 

 the age of the knot as deduced from 

 its own rings ? (As the tree may con- 

 tinue to live and grow indefinitely after 

 the bough which formed the knot died 

 or was cut away, there will probably 

 be no correspondence between the two 

 sets of rings, especially in the case of 

 old knots that have been covered up 

 and embedded 

 in the wood.) 



317. Section of tree 

 trunk showing knot. 



: 



The longer a dead branch remains 

 on a tree the more rings of growth 

 will form around it before covering 

 it up, and the greater will be the 

 disturbance caused by it. Hence, 

 timber trees should be pruned while 

 very young, and the parts removed 

 should be cut as close as possible to 

 the main branch or trunk. Some- 

 times knots injure lumber very 

 much by falling out and leaving the 

 holes that are so often seen in pine 

 boards. In other cases, however, 

 when the knots are very small, the grown in the open; 319, from 



. . . . , , tree grown in a dense forest. 



irregular markings caused by them 



add greatly to the beauty of the wood. The peculiar 

 marking of bird's-eye maple is caused by abortive buds 

 buried in the wood. 



- 



318 319 



318, 319. Diagrams of tree 

 trunks, showing knots of dif- 

 ferent ages: 318, from tree 



PRACTICAL QUESTIONS 



1. Name the principal timber trees of your neighborhood. What 

 gives to each its special value? 



2. Which is better for timber, a tree grown in the open, or one in 

 a forest, and why? (239.) 



3. What are the objects to be attained in pruning timber trees? 

 Orchard and ornamental trees? 



