ECONOMIC WOODS OP THE UNITED STATES 79 



a 2 Color yellowish-brown, not reddish. Texture 

 medium. Wood usually in small sizes, not straight- 

 grained, not highly resinous. Sp. gr. .54-.78, mostly 

 between .55 and .65. Larch, Tamarack, Hackma- 

 tack, Larix laricina (Du Roi) Koch., or L. americana 

 Michx. (N). 

 b 2 Color red to reddish-brown. Texture coarse and 

 harsh. Wood obtainable in large sizes, straight- 

 grained, sometimes extremely dense and very pitchy. 

 Sp. gr. .59-.83, mostly between .60 and .70. Western 

 Larch, Tamarack, L. occidentalis Nutt. (R). 

 b 1 Wood varying from very light and soft to moderately 

 so, with from slight to decided contrast between 

 seasonal growths; non-resinous. Texture fine. Lustre 

 satiny and finely dappled, especially on tangential sur- 

 face. Sapwood usually without distinct line of demar- 

 cation. Spruce. 16 

 a 2 Color white or very light, uniform, with little or no 

 contrast between heartwood and sapwood. Resin 

 ducts scarcely visible without lens. Sp. gr. .31-.53, 

 mostly between .35 and .45. 



a 3 Grain varying from extremely fine to medium.* 

 Red Spruce, Picea rubens Sarg., or P. rubra Diet. 

 (N) 17 ; Black Spruce, P. mariana Mill., or P. 

 nigra Link. (N). 

 b 3 Grain mostly coarse. White or Cat Spruce, P. 

 canadensis (Mill.) B. S. P., or P. alba Link. (N) f; 

 Engelmann Spruce, P. engelmanni Eng. (R). 

 b 2 Color reddish or pinkish, fading gradually outward 

 into sapwood; deepest in rays. Texture rather 

 wooly. Resin ducts fairly distinct. Sp. gr. .34-65, 

 mostly between .35 and .40. Sitka Spruce, P. 

 sitchensis (Bong.) T. & M. (Pn). 



* Since fineness of grain (i.e., width of growth rings) is largely determined 

 by external factors it is an unreliable diagnostic feature and is resorted to here 

 because constant features of distinction are apparently wanting and also be- 

 cause it is used to some extent by lumbermen. 



t The wood of the eastern spruces, particularly P. canadensis, rather 

 closely resembles that of the balsam fir, and the two are often associated both 

 in the forest and in the market. The peculiar dappled lustre of spruce and 

 the presence of resin ducts and ray tracheids are distinctive. 



