PINUS 313 



only, wholly composed of tracheids ; much contracted at the position 

 of the often interspersed and very narrow tracheids ; the parenchyma 

 cells unequal, oval, and somewhat variable ; the thin lateral walls 

 strongly incurved or convex, sometimes much inflated. 



A large tree 30-46 m. in height, with a trunk upwards of 1.50 m. in 



diameter. 

 Wood very light, soft, not strong, close and straight grained, and compact. 



Specific gravity 0.3908 



Percentage of ash residue 0.23 



Approximate relative fuel value 38.99 



Coefficient of elasticity in kilograms on millimeters . . 950. 



Ultimate transverse strength in kilograms 260. 



Ultimate resistance to longitudinal crushing in kilograms 5349. 



Resistance to indentation to 1.27 mm. in kilograms . . 1071. 

 (Sargent) 



A somewhat uncommon but valuable timber tree, usually below 3000 feet 

 elevation in British Columbia, but rising to 7000-10,000 feet in Cali- 

 fornia. Cceur D'Alene and Bitter Root Mountains of Idaho, to the valley 

 of the Flathead River, northern Montana: south along the Cascade Moun- 

 tains of Washington and Oregon, and the California Sierras to Calaveras 

 County (Sargent) ; Vancouver Island ; the Gold and Coast ranges of 

 British Columbia, disappearing at an elevation of 2235 feet (Macoun). 



9. P. flexilis, James 

 White Pine 



Transverse. Growth rings narrow, rather uniform. Summer wood very thin, 

 of 3-4 tracheids and open, the tracheids large, squarish, uniform. 

 Spring wood very open, the tracheids squarish, rather variable, the 

 walls thin. Medullary rays not prominent or numerous, i cell wide, 

 distant 2-8 rows of tracheids. Resin passages large, numerous, the 

 epithelium very thin-walled. 



Radial. Rays nonresinous ; the low, marginal, and sparingly interspersed 

 tracheids rather numerous. Parenchyma ray cells straight ; the upper 

 and lower walls with frequent, broad pits ; the terminal walls thin and 

 not pitted ; the lateral walls with large, oval, or oblong-lenticular pits, 

 1-2, or in the marginal cells more rarely 3-4, per tracheid, in the 

 summer wood reduced to I and lenticular. Bordered pits elliptical, 

 large, in i row, rather numerous. Pits on the tangential walls of the 

 summer wood numerous and prominent, broadly lenticular, especially 

 numerous on the outermost wall, becoming scattering within. Resin- 

 ous tracheids wanting. 



Tangential. Fusiform rays few, rather high and broad, the cells of the 

 inflated portion very thin-walled and often completely broken out. 

 Ordinary rays numerous, medium, nonresinous, not conspicuously 



