ECONOMIC WOODS OF THE UNITED STATES 79 



d? Radial walls of each ray-parenchyma cell with 1-2 

 large simple pits communicating with each adjacent 

 wood tracheid (Fig. 4). Woo d straight-grained: rate 

 of growth widely variable. White Pine Group.^ 

 Pinus strobus L. (N); monticola Dougl. (P); lam- 

 hertiana Dougl. (P); flexilis James (P); albicaulis 

 Eng. (R, P); strobiformis Eng. (R). 



a^ Color cream w hitat o reddish brown. Texture fine. 

 Resin ducts fairly conspicuous, appearing on longi- 

 tudinal surface as straw-colored or light-brown 

 lines. Without sugary exudations. Pits on lateral 

 walls of ray-parenchyma cells large, 1-2 (mostly 1) 

 per tracheid. White Pine. P- strobus L. (N),^ 

 monticola Dougl. (P). '^ ItM- xjJU^^^i, _ ( f'.\v4-t-*- 



b^ Color yellowish white to very light brown. Tex- 

 ture comparatively coarse. Resin ducts conspic- 

 uous, appearing on longitudinal surface as dark 

 lines. Sugary exudations^ and sugar pockets 

 common! Piis on lateral walls of ray-parenchyma 

 cells comparatively small, 1-2 (mostly 2) per 

 tracheid. Sugar Pine. P. lambertiana Dougl. (P).* 



b^ The radial walls of each parenchyma cell with 3-6 

 small semi-bordered pits communicating with each 

 adjacent wood tracheid (Fig. 5). Texture very fine. 

 Wood cross-grained and of very slow growth. Pox- 

 tail and Nut Pine Group. P. quadrifolia Pari. (P); 

 cembroides Zucc. (R); edulis Eng. (R)^; monophylla 

 T. &F. (R); balfourianaMuiT. (P); anstata Eng. (P) . 



)' Decided contrast between ea £ly_an d late woo d. Wood 

 very hard to rather soft; resinous; texture uneven; 

 color variable, but mostly darker^haii_nisoft__pines. 

 Upper and lower walls^f the sinairand numerous ray 

 tracheids dentate or reticulate (Figs. 6, 7). Pits rarely 

 present on tangential walls of the tracheids of the late 

 wood. Pitch Pine Group. 



a^ The radial walls of each ray-parenchyma cell with 1-2 

 large simple pits communicating with each adjacent 

 wood tracheid (Fig. 6). Wood light, rather soft, 

 fairly strong, medium-textured, not highly resinous. 



