PINUS 343 



39. P. taeda, Linn. 

 Loblolly Pine. Old Field Pine 



Transverse. Growth rings broad. Summer wood open or sometimes rather 

 dense, often double and often equal to the spring wood, from which the 

 transition is abrupt ; the tracheids large, strongly unequal but in rather 

 regular rows. Spring tracheids large, squarish, the walls thin. Resin 

 passages numerous, chiefly in the summer wood, very large ; the epithe- 

 lium composed of very thin-walled, sometimes resinous cells, chiefly in 

 i row and strongly compressed upon the face of the tracheid structure, 

 more rarely becoming 2-rowed in part and forming an eccentric tract 

 of limited extent. Medullary rays rather prominent, broad, i cell wide, 

 distant 2-8 rows of tracheids. 



Radial. Rays nonresinous ; the tracheids sometimes predominant in the higher 

 rays, but often interspersed, low and unequal throughout, sparingly, 

 rarely strongly reticulated. Ray cells of two kinds: (i) cells rare and 

 occurring only (?) in the low rays, where they are conterminous with the 

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

 thick and strongly but incompletely pitted ; the lateral walls with round 

 or oval pits, upwards of 6 per tracheid; (2) cells variously fusiform, 

 often straight ; the terminal, upper, and lower walls very thin and com- 

 monly much broken out ; the lateral walls with variable, oval, or lentic- 

 ular pits, 1-6, chiefly 2-4, per tracheid, in the summer wood commonly 

 reduced to I. Bordered pits in I or 2 rows or often i row or pairs, 

 elliptical. Pits on the tangential w r alls of the summer wood wholly 

 wanting. The tracheids of the summer wood sometimes exhibit a dis- 

 tinct tendency toward the formation of spirals. 



Tangential. Fusiform rays rather high and narrow', the terminals acute or 

 prolonged and finally wholly composed of small tracheids ; the cells of 

 the inflated portion commonly wanting. Ordinary rays medium and 

 presenting two principal aspects: (i) higher rays composed of thin- 

 walled parenchyma cells chiefly broken out, with very small, terminal, 

 and interspersed tracheids, the latter causing local contractions ; and 

 (2) lower rays of thin-walled parenchyma much broken out, rarely 

 showing a thick-walled parenchyma cell, and small, terminal tracheids. 



A large tree 24-46 m. high, with a trunk upwards of 1.50 m. in diameter. 

 Wood light, not strong, brittle and very coarse grained, not durable. 



Specific gravity O-544 1 



Percentage of ash residue 0.26 



Approximate relative fuel value 54- 2 7 



Coefficient of elasticity in kilograms on millimeters . . 1128. 



Ultimate transverse strength in kilograms 377. 



Ultimate resistance to longitudinal crushing in kilograms 6834. 



Resistance to indentation ^o 1.27 mm. in kilograms . . . I7J9- 

 (Sargent) 



Low, wet clay or sandy soil ; southern Delaware to Tampa Bay, Florida, 

 generally near the coast ; westward through the Gulf States to the valley 

 of the Colorado River, Texas, and northward through southern Arkansas 

 to the valley of the Arkansas River (Sargent). 



