ECONOMIC WOODS OF THE UNITED STATES 83 



b^ Growtli. ringjs of medium widt h, though often very 

 narrow near centre of tree. 



Red Spruce. P- rubens Sarg. (N) . 



c^ Growth rmgs mostly ve ry narrow throughout . 



Black Spruce. P. mariana Mill. (N). 



b^_Color distinctly reddkji, fading gradually outward. 

 Moderate contrast in density between early and late 

 wood; transition gradual. Resin ducts plainly visibl e 

 toj inajde d eyg, appearing on cross section as white dots 

 against colored background. 



Sitka Spruce. P. sitchensis T.^ M. (P). 



B Resin ducts normally absent ; sometimes present as a result of 

 injury, the vertical ducts arranged tangentialJy in a compact 

 row (Fig. 10). Ray tracheids present or absent. 

 1 With clear dema rcation in color bet ween heartwood and sap - 

 wood. ^"^ ~~ 



a Resin cells numerous, often conspicuous to unaided eye. 

 Tracheids without spirals. Wood light an d..spJjLto moder- 

 ately so; lustre dull. 



a' Odorless and tasteless. Texture coarse and harsh. 

 Bapwood thin, straw-colored to nearly white, often 

 streaked with fine purplish lines of resin cells. Resin 

 masses in resin cells appear (under lens) on longitudinal 

 surface as rows of black or amber beads. Sequoia. '° 



a^ Woo d deeply colored, purplish. G rowth rings mostly 

 very narrow. Texture fairly coarse. 



Big Tree. Sequoia washingtonianaSxidw. (P).'" 



b^ Wood less deeply colored; light cherry. Growth 

 rmgs variable from wide to narrow. Tixture very 

 coarse. Resin masses more prominent than in 

 preceding. Redwood. S. sempervirens Engl. (P)." 



b^ j3dor aromatic, pungent. Texture fine to very fine . 

 Sapwood white or nearly so, HOC fefffeaked'; Resm ceils 

 small, without bead-like appearance. 



a^ Growth rings uniform, usually rather wide; late wood 

 rather thin, but very conspicuous; rarely~double3. 

 Resin cells fairly numerous, zonate, mostly in late 



