QUEBRACHO WOOD AND ITS SUBSTITUTES. 11 



diameter of from 1 to 3 feet, and remarkable for its erect stem and 

 wide spreading crown. It is usually less bulky than quebracho, 

 and branches nearer the ground, features which help to distinguish it 

 in the forest. 



The wood is strong, hard, and very heavy (specific gravity from 0.88 

 to 1.1), very close-grained, yellowish white in color, with a pinkish or 

 rosy tint. It is not very durable in contact with the soil, yet much in 

 demand for fence posts, rafters, flooring, railroad trucks, cross- 

 ties, cabinet work, turnery, hubs, spokes, and cogwheels. Its dense, 

 uniform structure^ makes it suitable as a substitute for boxwood 

 (Buxus semperwrens L.) in wood engraving. Unless very carefully 

 seasoned, however, it is likely to warp and twist, and is said to be 

 subject to insect attack. 



RED QUEBRACHO (QUEBRACHO COLORADO). 



Red quebracho is also abundant throughout quebracho's range. 

 Its wood when freshly cut is red, but becomes dark brown with age. 

 It is used for practically the same purposes as white quebracho. 

 Although in general its structural characters are similar to those of the 

 former, it is said to be more durable in contact with the soil. While 

 red quebracho may at first sight be mistaken for quebracho, its struc- 

 tural characters distinguish it. Moreover, its commercial importance 

 is relatively so small that it is seldom mixed with the other wood. 



KEY FOB THE IDENTIFICATION OF QUEBRACHO WOOD AND ITS 



SUBSTITUTES. 



As an aid in distinguishing the wood of quebracho from that of the 

 two inferior species, a key is given, in which are included such gross 

 characters of the woods as may be seen in a smooth transverse section 

 with the aid of a hand lens. For the use of students, several of the 

 minute characters, which can be seen only under the high power of a 

 compound microscope, are also included. Plates I and II show mag- 

 nified transverse sections of quebracho and white quebracho wood. 

 The structure of red quebracho is so similar to that of white that an 

 illustration of it is unnecessary. 



Pores (vessels) small (0.03 to 0.09 millimeters), open, and regularly dis- 

 tributed; tangential bands of large pores usually alternating with 

 bands of smaller pores. Wood-parenchyma fibers abundant, scat- 

 tered throughout the wood, often arranged in short tangential 

 lines. Wood fibers 0.9 to 1.5 millimeters long. Heartwood dark 

 pink, hard, and heavy (about 62 pounds per cubic foot). 



(Aspidosperma quelracho-llanco Schlecht.) 



Similar in structure to above, but heartwood red, becoming dark 

 brown with age. 



(Aspidosperma quebracho-colorado Schlecht.) 



