98 ECONOMIC WOODS OF THE UNITED STATES 



b 3 Wood parenchyma about pores; not in tangential 

 lines. No "ripple marks." Pores not resinous 

 or gummy. 



a 4 Wood extremely dense; sp. gr. .83; fibres much 

 interlaced. Alternate bands of wood varying 

 in density and direction of fibre common, but 

 growth rings not sharply defined. Pores con- 

 spicuous, irregularly distributed, often in diag- 

 onal chains which may be zig-zag; tyloses 

 present. Rays very fine, indistinct. Vessels 

 without spirals; perforations simple; pits into ray cells 

 half-bordered or simple. Rays 1-2, occasionally more, 

 cells wide and 1-25 cells high; somewhat heteroge- 

 neous. Blue Gum, Eucalyptus globulus Lab. (Int., 

 Ps, T). 47 



b 4 Wood moderately dense, sp. gr. .65; grain vari- 

 able from straight to wavy. Growth rings dis- 

 tinct, due to denser band of late wood. Pores 

 rather small, mostly in radial groups of 2-6, 

 fairly uniformly distributed; tyloses absent. 

 Rays fine but distinct. Vessels without spirals; 

 perforations simple; pits into ray cells half-bordered or 

 simple. Rays 2-3 seriate, few to 25 cells high; mostly 

 homogeneous. California Laurel, Pepperwood, 

 Umbellaria calif ornica (H. & A.) Nutt. (P). 

 b 1 Some of the rays usually very broad.* Pores some- 

 what variable in size but distinct; arranged in radial 

 lines or bands between broad rays, extending across 

 the growth ring and often continuous from one ring to 

 another. Wood parenchyma commonly in concentric 

 lines as well as about pores, frequently conspicuous. 

 Wood very dense; sp. gr. .85-.95. Color light to dark 

 brown, sometimes tinged with red. Evergreen and 

 Live Oak Group. 48 Quercus virginiana Mill. (8); Q. 

 agrifolia Nee. (Ps); Q. chrysolepis Liebm. (Ps.); Q. 

 wislizeni A. de C. (Ps); Tanbark Oak, Q. densiflora 

 H. & A., or Pasania densiflora Oerst. (P). 49 



* It is not uncommon to find specimens of the woods of this group without 

 broad rays, though in such cases there is a tendency to aggregation of the uni- 

 seriate rays. 



