260 ANATOMY OF THE GYMNOSPERMS 



California, Mt. Shasta, south along the western slopes of the Sierra Nevadas 

 to Kern County; forming extensive forests between 4900 and 8000 feet 

 elevation ; becoming less common south of Mt. Shasta, and reaching an 

 extreme elevation of 10,000 feet (Sargent). 



6. A. amabilis, Forbes 

 While Fir 



Transverse. Growth rings narrow, the structure usually very open through- 

 out. Summer wood upwards of one half the spring wood, into which 

 it passes very gradually. Spring tracheids large, thin-walled, very 

 squarish, and uniform in regular rows. Resin cells few and widely 

 scattering on the outer face of the summer wood, where they may be 

 distinguished by (i) the sieve-plate structure of the terminal wall, and 

 (2) their often advanced position. Medullary rays rather prominent, 

 not resinous, i cell wide, numerous, distant 29 rows of tracheids. 



Radial. Rays nonresinous, wholly devoid of tracheids. Ray cells chiefly 

 straight except in the summer wood, equal to 3-7 spring tracheids, 

 becoming much shorter in the summer wood ; the upper and lower 

 walls thick, unequal, and coarsely but very unequally pitted through- 

 out ; the terminal walls strongly pitted throughout ; the lateral walls 

 with small, round or oval pits, which toward the summer wood show a 

 prominent and broad border, and the broadly lenticular orifice becomes 

 reduced to a slit, 1-2, rarely 3, or in the marginal cells sometimes 5, 

 per tracheid. Bordered pits in i row, sometimes in pairs, variable, 

 elliptical. Pits on the tangential walls of the summer tracheids 

 numerous and rather small, but broadly lenticular, open. Resin cells 

 frequently present on the outer face of the summer wood, sometimes 

 conterminous with similar tracheids ; usually very narrow and long, 

 12.5-25 fj, wide, and upwards of 600 p. long. 



Tangential. Rays medium to high, the cells uniform, chiefly oval, more 

 rarely round or narrowly oval, sometimes in pairs. 



A tree 30-45 m. high, with a trunk upwards of 1.20 m. in diameter. 

 Wood light, hard, not strong, close grained, compact. 



Relative specific gravity 0.4228 



Percentage of ash residue 0.23 



Approximate relative fuel value 42.18 



Coefficient of elasticity in kilograms on millimeters . . 1260. 



Ultimate transverse strength in kilograms 338. 



Ultimate resistance to longitudinal crushing in kilograms 7480. 



Resistance to indentation to 1.27 mm. in kilograms . . 1029. 

 (Sargent) 



Valley of the Fraser River and probably farther north ; south along the 

 Cascade Mountains of Washington and Oregon (Sargent). 



