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Tangential Section. Natural Size 



Interior of Block, one-Half Natural Size 

 SECTIONS OF SUGAR MAPLE, SHOWING UIRDS-EYE 



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Burls and BircTs-Eye 



One of the most beautiful of all ligured woods is that produced by 

 burls. Burls are abnormal growths or excrescences common to almost 

 every species of tree, although in only a comparatively few cases are 

 they of merchantable character. They may arise anywhere on a tree, 

 but those of greatest value are at the root collar, usually just below 

 the surface of the ground. 



Burls are produced as a result of some injury, such as forest fires, 

 insect attacks, gnawing of animals, excessive pruning, etc. The 

 effect of the injury is to stimulate the growth of dormant buds or 

 to give rise to a great many new ones which can not develop into 

 branches but do form a gnarly and interwoven mass of woody tissue 

 of very intricate design. The wood is very dense and hard. Inside 

 the bark the surface of a burl is covered with spiny warts — the 

 points where the buds emerge. 



A dormant bud is one which ne\er developed into a shoot or branch. 

 Only a limited number of the buds in the axis of the leaves and bud 

 scales of the shoot develop, since there would be no room for them 

 to grow even if there were food enough to nourish them. The 

 majority, and especially those toward the base of a shoot, persist 

 for a longer or shorter time — sometimes for a century or more in 

 trees with smooth bark — and only under certain conditions do they 

 burst forth into new shoots. 



In order that such buds might remain alive and not be covered 

 up by the woody layers it is necessary that they grow in length each 

 year just enough to keep to the surface. In the center of each bud 

 is a small cylinder of pith and around it is a small mound of wood, 

 the fibers of which run in different directions from the rest of the 

 wood. When cut across, the pith of tlie bud appears as a dark speck 

 surrounded by a small mass of fibers on end, producing a figure 

 known as "bird's-eye." 



In addition to these dormant buds new ones may arise which are 

 known as adventitious buds. If there is suflicient nourishment and 

 conditions are favorable they will grow into shoots, but in the case 

 of burl formation they make a short growth, die at the tip and their 

 places are taken by others, which repeat the performance year after 

 year. The consequence is an extremely complex nest of buds, all 

 capable of growing in thickness to some extent but not growing out 



in length. In course of time this burl may attain dimensions measur- 

 able by ipet and weighing hundreds or even thousands of pounds. 



Burls growing on the upper portion of a tree are usually without 

 value for cabinet work on account of defects due to insects, included 

 bark or other causes. Valuable root burls are turnip-shaped or 

 sometimes one sided. They are rooted on the under side and edges, 

 and at the place of attachment of a large root the grain is usually 

 straight, thus detracting from the value of the burl. It requires 

 long experience to be able to judge, from external appearances, how 

 a burl is going to open up, and in cutting or slicing the veneer very 

 careful manipulation is necessary to obtain the largest pieces with 

 the finest figure. 



Trees producing merchantable burls are black walnut, black cherry, 

 ash, birch, alder, oak and redwood. Walnut burls are most sought 

 after and their value in the rough ranges from ten or fifteen cents 

 a pound upward. Trees producing burls are usually rather dwarfed 

 and stunted and grow in the open rather than in dense woods. In 

 fact the presence of a large burl is very likely to cause the tree to 

 be poorly developed, and in a forest such trees would sooner or later 

 be shaded out. 



Burls are common on the walnut trees of Austria, Turkey and 

 Italy, and owing to their finely mottled and beautiful figure, are 

 nmch sought after for cabinet purposes. According to LasLett 

 those of the best quality have been known to realize from $250 to 

 $300 per ton in the rough. In Algeria fires and grazing, which have 

 destroyed the finest forests of Thuya, cause large and valuable burls. 

 Formerly they were mnch sought after for the manufacture of fancy 

 articles of furniture, but as it was necessary to destroy large areas 

 of timber to find the beautiful specimens, the wasteful exploitation 

 was finally abandoned. French cabinet makers use the burls of the 

 hazel tree of the Levant to considerable e.xtent. 



BIRD'S-EYE 



Everyone is familiar with the figure known as bird's-eye, which 

 is particularly common in sugar maple. Almost every tree of this 

 species contains at least a few bird 's-eyes, though in only a com- 

 paratively few cases are they abundant enough to give value to the 





IT 



Radial Section. Natural Size Cross Section, Natural Size 



SECTIONS OF SUGAR MAPLE, SHOWING BIRD'S-EYE 



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