PINUS 329 



A tree 18-24 m. high, with a trunk upwards of 1.20 m. in diameter. 

 Wood light, soft, not strong, close and straight grained, easily worked, 

 compact, not durable. 



Specific gravity 0.4096 



Percentage of ash residue 0.32 



Approximate relative fuel value 40-83 



Coefficient of elasticity in kilograms on millimeters . . 771. 



Ultimate transverse strength in kilograms 241. 



Ultimate resistance to longitudinal crushing in kilograms 5328. 



Resistance to indentation to 1.27 mm. in kilograms . . 1379. 

 (Sargent) 



An Alpine tree somewhat localized in the Rocky Mountains of British 

 Columbia at elevations of 3500-4000 feet, and northward to latitude 

 62 (Macoun) ; mountain ranges of Washington, Oregon, and the Sierra 

 Nevadas of California to San Jacinto ; southward through the moun- 

 tains of Idaho, Montana, Wyoming, Colorado, and Utah to New Mexico 

 and northern Arizona. The tree attains it greatest development in the 

 California Sierras, in the interior occurring on dry, gravelly soil cover- 

 ing immense areas. In the Rocky Mountain region it occupies the 

 borders of moist Alpine meadows between 6000 and 9000 feet elevation 

 (Sargent). 



26. P. arizonica, Engelm. 

 Yellow Pine 



Transverse. Growth rings chiefly thick but variable, often double. Summer 

 wood thin, of about 4-10 tracheids but very variable, usually very 

 open ; the tracheids very unequal, now small and round or again large 

 and much compressed, often in very irregular rows ; transition from 

 the spring wood somewhat gradual. Spring tracheids large, hexagonal, 

 uniform, in regular rows, the walls thin. Resin passages very large, 

 rather abundant; the epithelium in 2 rows, that next the canal com- 

 posed of large and rather thin-walled cells which are immediately 

 bounded by a layer of rather thick-walled, large, rounded, and often 

 resinous cells. Medullary rays broad, i cell wide, rather prominent, 

 sparingly and locally resinous, distant 2-10 rows of tracheids. 



Radial. Rays locally resinous ; the ray tracheids strongly predominant, 

 strongly dentate, and somewhat reticulated in the summer wood. Ray 

 cells sparingly fusiform and of two kinds: (i) rather numerous, the 

 terminal walls thin and entire ; the upper and lower walls rather thick 

 and very coarsely pitted ; the lateral walls with variously oval, oblong, 

 or lenticular pits, 2-4, chiefly 4, per tracheid, becoming 2 in the sum- 

 mer wood ; (2) the cells equal to about 5 spring tracheids, the terminal 

 walls thin and entire ; the upper and lower walls thin and entire ; the 

 lateral walls with oval, oblong, or round pits, 2-4, chiefly 4, per tra- 

 cheid, becoming 2 in the summer wood. Bordered pits in I row, 

 sometimes in pairs, often numerous, elliptical. Pits on the tangential 

 walls of the summer wood wholly wanting. 



