336 HORTICULTURE, FORESTRY, FLORICULTURE 



,either die or remain "dormant," often for a hundred years, to spring 

 into life when necessary. 



The fact that each ordinary limb starts as a bud from the pith 

 is an important one to the timber grower ; it explains knotty timber 

 and gives him the hint that in order to obtain clear timber the 

 branches first formed must be soon removed, either by the knife or 

 by proper shading, which kills the branches and thus "clears" the 

 shaft. The planter has it also in his power to influence the form 

 development of the tree by removing some of the buds, giving 

 thereby better chance to the remaining ones. This pruning of buds 

 is, where practicable, often better practice than the pruning of limbs. 



Since the tree does not grow in length except by its buds it is 

 evident that a limb which started to grow at the height of 6 feet has 

 its base always 6 feet from the ground, and if allowed to grow to 

 size, must be surrounded by the wood which accumulates on the 

 main stem or trunk. If a limb is killed and broken off early, only 

 a slender stub composed entirely of rapidly decaying sapwood, is 

 left, occasioning, therefore, only a small defect in the heart of the 

 tree; but if left to grow to considerable age, the base of the limb is 

 incased by the wood of the stem, which, when the tree is cut into 

 lumber, appears as a knot. The longer the limb has been allowed 

 to grow, the farther out is the timber knotty and the thicker is the 

 knot. If the limb remains alive, the knot is "sound," losely grown 

 together with the fibers of the tree. If the limb died off, the re- 

 maining stub may behave in different ways. In pines it will be 

 largely composed of heartwod, very resinous and durable ; separated 

 from the fibers of the overgrowing wood, it forms a "loose" knot, 

 which is apt to fall out of a board, leaving a hole. 



In broad-leaved trees, where no resin assists in the process of 

 healing, the stub is apt to decay, and this decay, caused by the 

 growth of fungi, is apt to penetrate into the tree. In parks and 

 orchards, pruning is resorted to, and the cuts are painted or tarred 

 to avoid tne decay. In well-managed forests and dense woods in 

 general, the light is cut off, the limb is killed when young and 

 breaks away, the shaft "clears itself," and the sound trunk furnishes 

 a good grade of material. The difference in development of the 

 branch system, whether in full enjoyment of light, in open stand, 

 or with the side light cut off, in dense position, is very apparent. 



Both trees start alike; the one retains its branches, the other 

 loses them gradually, the stubs being in time overgrown; finally 

 the second has a clear shaft, with a crown concentrated at the top, 

 while the first is beset with branches and branch stubs for its whole 

 length. Since the branches grow in more or less regular whorls, sev- 

 eral knots, stumps, or limbs are met every 6 to 24 inches. 



Hence, in forest planting, trees are placed and kept for some 

 time close together, in order to decrease the branching in the lower 

 part of the tree and thus produce a clean bole and clear lumber. 



Growth in Thickness. The young seedling and the young 

 shoot of the older tree much resemble in interior structure that of 

 any herbaceous plant, being composed of a large amount of pith, 



