3l8 ANATOMY OF THE GYMNOSPERMS 



Section II. Hard Pines 



14. P. clausa, Sarg. 

 Sand Pine. Scrub Pine. Spruce Pine 



Transverse. Growth rings thick, often double. Summer wood dense, rarely 

 somewhat open, often exceeding the spring wood, from which the tran- 

 sition is usually very abrupt, and within the same section showing both 

 open and dense structure ; the tracheids rounded, unequal, and often in 

 irregular rows. Spring tracheids hexagonal, not very uniform, the walls 

 rather thickish. Resin passages large, chiefly in the summer wood ; 

 the epithelium composed of large, round, and thin-walled cells chiefly 

 in i row, occasionally in 2 rows and forming more or less eccentric 

 tracts. Medullary rays not very prominent or broad, i cell wide, distant 

 2-8 rows of tracheids. 



Radial. Rays nonresinous ; the tracheids often predominant and when 

 interspersed often becoming very low, strongly reticulated throughout. 

 Ray cells of one kind only, the cells rather broad, long fusiform ; the 

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

 the lateral walls with very variable, lenticular, or oval pits, 1-5, chiefly 

 2-3, per tracheid, in the summer wood reduced to i. Bordered pits 

 conspicuously in 1-2 rows, elliptical, in the summer wood abruptly 

 reduced to 14.4 /JL, and finally to 7.2 p.. Pits on the tangential walls of 

 the summer wood wholly wanting. 



Tangential. Fusiform rays medium to high, rather broad ; the terminals 

 acute, somewhat prolonged, and composed of few tracheids ; the 

 inflated portion composed of very large, rounded, and usually extremely 

 thin-walled cells among which there may be an occasional tracheid. 

 Ordinary rays numerous and presenting three principal aspects: (i) low 

 rays with large oval, central parenchyma cells and small, terminal tra- 

 cheids, fusiform ; (2) higher rays composed of large, squarish-celled 

 and thin-walled parenchyma, with a few narrower, terminal tracheids ; 

 and (3) the highest rays composed of large, thin-walled, oval, and broad 

 parenchyma cells with small terminal and smaller interspersed tracheids 

 causing local contractions. 



A tree 21-24 m - high, with a trunk upwards of .75 m. in diameter. 

 Wood light, soft, not strong, brittle. 



Specific gravity 0.5576 



Percentage of ash residue 0.31 



Approximate relative fuel value 55-9 



Coefficient of elasticity in kilograms on millimeters . . 543. 



Ultimate transverse strength in kilograms 214. 



Ultimate resistance to longitudinal crushing in kilograms 6028. 



Resistance to indentation to 1.27 mm. in kilograms . . 2100. 

 (Sargent) 



Barren, sandy dunes and ridges of Florida ; shores of Pensacola Bay and 

 southward within 30 miles of the coast to Pease Creek ; on the east 

 coast occupying a narrow ridge south of St. Augustine (Sargent). 



