DESCKIPTION OF WOOD. 



THE WOOD.' 



The wood of the Loiifjloaf I'iiic is heavier and stioDK'ei' than th.at of any other pine offered in 

 the inarliet. The average weiglitof the kihj-dry wood is about ;>S pounds, tliat of the hiniber where 

 the outer lighter jjortion of the log is largely cut away about 40 pounds, per cubic foot. Tlie 

 kiln dry wood of the butt weighs about 45 pounds per cubic foot; that of a log .'50 to fiO feet from 

 the ground only about 'Mi pounds, a decrease of weight (and with it of strength) of about 2."» ])er 

 cent. Similarly the wood of inner portions of a log are 15 to 20 per cent heavier than those of the 

 outer portions; or, in other words, the wood laid on when the tree is young is heavier than that 

 laid on when it is old, quite contrary to the common l)elief wliich seems to associate the light 

 sapwood color of the young sa])ling with inferior material. The wood shrinks about 10 per cent of 

 its volume in drying, about to 7 per cent along the rings (tangentially) and 3 to 4 per cent along 

 the radius; seasons easily and without great injury. As iu other pines, the greatest amount of 

 water is contained in the sui)woo(l, varying from 30 to 50 per cent of the weight of the fresh wood, 

 while the heartwood contains but about 20 per cent. 



In its stiffness and strength the wood is remarkable. The average of a great number of tests 

 indicates for the dry wood of Longleaf Pine au elasticity of 1,540,000 pounds per square inch; 

 strength in cross breaking, 10,000 pounds per square inch; strength in compression, 0,850 pounds 

 per square iuch; strength in tension, 15,200 pounds per square inch; strength iu shearing, 700 

 ])Ounds per square inch. 



In its structure the wood of the Longleaf Pine resembles that of the other Southern pines. 

 Sapwood and heartwood are well defined; on the fresh cross section the former is light yellowish 

 white, the latter a yellowish brown; drops of limpid resin ooze from every resin duct in the sap 

 wood, the surface of the heartwood remains dry (exceptions only in "lightwood"). The sapwood 

 contains much more water, but is far less resinous than the heartwood. This latter contains 5 to 

 10 per cent of resin (1 i)art turpentine to 15 to 20 parts resin), while in the former the resin 

 rarely exceeds 2 per cent. If not kiludried, fresh sapwood rapidly "blues" on exposure; heart- 

 wood does not, and iu general excels the sapwood in durability. On drying, the sapwood shrinks 

 more than the heartwood of the same weight. Contrary to common belief, the wood substance, or 

 cell wall, is not increased in the change from sapwood to heartwood, the walls do not grow thicker, 

 the cavities of the cells do not lill up with foreign matter, nor does the strength of the wood seem 

 to be increased by the cluiTige. In general the width of the sapwood is greatest iu young and 

 thrifty trees, grows smaller iu old and stunted trees, is greatest iu the lower parts of the stem and 

 smaller in the top and branches. In old logs the sapwood is made up of from 70 to 100 rings, 

 showing that the wood of any one ring remains iu older trees seventy to one hundred years in the 

 sapwood ciinditiou before it changes to heartwood. In young trees this period is much shorter, 

 twenty five to forty years commonly sufficing for thrifty trees at the age of sixty to seventy years, 

 but in stunted individuals it is materially prolonged. The share of the sapwood in the total volume 

 of the stem is always considerable; even in typical old trees of tliis species it forms 4(» per cent 

 and more, while thrifty stems under one hundred years are practically all sapwood. 



The annual, or yearly, rings are clearly defined ; they are widest near the pith .and grow rather 

 unifoiiuly narrower toward the bark. In the inner part a width of one twelfth of an inch is quite 

 common ; the rings near the bark of old logs usually measure less than one twenty- fifth of an inch, 

 often scarcely one fiftieth of an inch. For old trees the average width for the entire stem may be 

 set at about one twentieth to one-twenty fifth of an inch. Each ring consists of two well-marked 

 parts, an inner, softer, whiter part, the springwood, and an outer, harder, and darker portion, the 

 sunimerwood, so called because formed during the latter part of the growing season. 



The amount of the sunimerwood in each ring differs in dilfereut parts of the tree. It forms 

 about 45 per cent of the volume of all the wood of the stump, and only about 24 per cent of the 

 wood 00 feet from the butt. It is greater in the heavy inuer part of an old log than in the lighter 

 outer portions, and being of a darker color furnishes a convenient means of distinguishing lieavy 

 wood. In its finer anatomy (histology) the wood resembles that of the other pines of tlie Iwda 

 group. (For the details of structure see the comparative study by Mr. Koth appended to these 

 monographs.) 



'This statement is furnished hy Mr. Filil)ert Roth, in charge of timber investigations in the Division of Forestry. 



