PINUS 317 



13. P. albicaulis, Engelm. 

 White Pine 



Transverse. Growth rings medium, uniform. Summer wood very thin and 

 open, the tracheids in regular rows, squarish, the transition from the 

 spring wood very gradual. Spring tracheids large, squarish-hexagonal, 

 rather uniform in regular rows, rather thin-walled. Medullary rays 

 rather broad, I cell wide, somewhat prominent, distant 2-8 rows of 

 tracheids. Resin passages medium, rather numerous, the prominent 

 and somewhat resinous epithelium composed of large and thin-walled 

 cells. Resinous tracheids often present but not prominent, forming 

 radial series contiguous to the medullary rays. 



Radial. Rays nonresinous ; the tracheids long and low, marginal, rarely 

 interspersed. Parenchyma ray cells straight ; the upper and lower walls 

 medium, variable, and with variable, often distant but chiefly broad 

 pits ; the terminal walls thin and not pitted ; the lateral walls with large, 

 oval, or broadly lenticular pits, 1-2, chiefly i, per tracheid throughout. 

 Bordered pits numerous, large, round, in i row. Pits on the tangential 

 walls of the summer wood not very numerous, rather small and flat, 

 chiefly on the outermost walls. Resinous tracheids somewhat numerous 

 and prominent, the resin forming plates opposite the medullary rays 

 and simulating Sanio's bands. 



Tangential. Fusiform rays high, rather narrow, the cells of the inflated 

 portion medium to small and thin-walled. Ordinary rays rather numer- 

 ous, medium, nonresinous, somewhat contracted at the position of the 

 occasionally interspersed and rather narrower tracheids ; the cells 

 rather equal and oval or oblong, the walls thin, often concave, more 

 rarely convex. Resinous tracheids somewhat prominent, the resin in 

 plates simulating Sanio's bands. 



A small Alpine tree, 6-12 m. high, with a trunk rarely .60 m. in diameter. 

 Wood light, soft, not strong, brittle, close grained, and compact. 



Specific gravity 0.4165 



Percentage of ash residue 0.27 



Approximate relative fuel value 4' -54 



Coefficient of elasticity in kilograms on millimeters . . 512. 



Ultimate transverse strength in kilograms 249. 



Ultimate resistance to longitudinal crushing in kilograms 5296. 



Resistance to indentation to 1.27 mm. in kilograms . . 1716. 

 (Sargent) 



Rocky Mountains of British Columbia between 6000 and 7000 feet eleva- 

 tion, northward to latitude 53 (Macoun) ; Cascade and Blue mountains 

 of Washington and Oregon ; Scott's Mountain, Mt. Shasta, and the high 

 peaks of the Sierra Nevadas to Mt. San Bernardino, California. Dry, 

 gravelly ridges at the extreme limit of growth, in the San Bernardino 

 Mountains attaining an elevation of 10,500 feet, and at the highest eleva- 

 tions becoming a prostrate shrub (Sargent). 



