308 ANATOMY OF THE GYMNOSPERMS 



from round to oval or oblong, those of the low rays often three times 

 higher than wide, those of the higher rays sometimes twice the width 

 of others. 



A small, bushy tree 4-6 m. high, with a trunk upwards of I m. in diameter. 

 Wood light, soft, weak, brittle, close grained, and compact. 



Specific gravity 0.5658 



Percentage of ash residue 0.68 



Approximate relative fuel value 56.20 



Coefficient of elasticity in kilograms on millimeters . . 435. 



Ultimate transverse strength in kilograms 123. 



Ultimate resistance to longitudinal crushing in kilograms 4389. 



Resistance to indentation to 1.27 mm. in kilograms . . 2713. 

 (Sargent) 



Dry gravelly slopes and mesas between 3000 and 6000 feet elevation. Near 

 Lake Utah, to the eastern foothills of the California Sierras, and south 

 along the mountain ranges of the Great Basin to the San Francisco 

 Mountains of eastern Arizona (Sargent). 



4. P. Balfouriana, A. Murr. 



Foxtail Pine 



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

 out. Summer wood thin, of 2-6 tracheids and open, the tracheids 

 large in regular rows, uniform, the transition from the spring wood 

 gradual. Spring tracheids rather large, very thin-walled, hexagonal, 

 chiefly in regular rows, but conspicuously unequal. Medullary rays 

 rather prominent and numerous, broad, i cell wide, distant 2-8 rows of 

 tracheids. Resin passages medium, rather numerous, widely scatter- 

 ing, the somewhat extensive epithelium composed of large, thin-walled, 

 more or less resinous cells. 



Radial. Rays sparingly resinous ; the tracheids rather numerous, marginal, 

 rarely interspersed. Parenchyma ray cells short and straight ; the upper 

 and lower walls thick and very strongly pitted ; the lateral walls with 

 numerous, small, round, or oval pits, at first with a prominent border 

 and narrowly lenticular, prolonged orifice, the border becoming obscure 

 and variable toward the summer wood, and the orifice broader, 1-5 per 

 tracheid, finally reduced to 1-2 in the summer wood. Bordered pits 

 numerous and round, in i row, nearly as broad as the tracheid. Pits on 

 the tangential walls of the summer wood very numerous and contig- 

 uous on the outermost wall, becoming scattering in the older tracheids, 

 small but rather broadly lenticular. Resinous tracheids wanting. 



Tangential. Fusiform rays narrow, the cells of the inflated portion large, 

 thin-walled, resinous, the resin passage not large. Ordinary rays 

 medium to high, rather broad, nonresinous, and somewhat contracted 

 by the rather narrower, smaller, and occasionally interspersed tra- 

 cheids; the thick-walled cells very equal and uniform, narrowly oval to 

 oblong. 



