WOOD OF CUliAN PINE. 79 



The triangular black rougliisli seeds 2^ to a little over 3 lines long, with a few faint ridges; 

 tlie biDwii, obtuse, and somewhat oblique wing (PI. XI, <>,/, g) abimt 1 inch in Icn-jth is deciduous 

 in germination. This species at all stages of growth can be distinguished from the Jjoblolly fine 

 by the deep-green foliage, the glaucous hue of the young, tender shoots, and varying number of 

 leaves in a bundle — from the Longleaf Pine by the thinner, almost smooth, terminal buds, and in 

 the adult state, from both of these species, with which it is found frequently associated, by its 

 cones. 



THE WOOD. 



As iu the Loblolly, the sapwood is wide in the young trees, measuring usually about 4 inches 

 and forming in thrifty trees fifty to seventy years old about 80 ]jer cent of the total volume. As 

 the trees grow older, however, this preponderance of sapwood ceases, and iu trees one hundred 

 and fifty to two hundred jcars old only 35 to 50 per cent of the total volume of the trunk was found 

 to be composed of sapwood. xVs iu the case of the pines already nuMitioned, the change from sap- 

 wood to heartwood begins when the tree (or disk) is about twenty-five to thirty years old, and the 

 process is retarded as the tree (or disk) grows older, so that when any fnie disk is sixty years old 

 the sapwood contains about forty rings, and reaches eighty rings or more by the time the tree (or 

 disk) is two hundred years of age. As a consequence the sapwood of the disks of the main part 

 of the trunk in old trees is formed of nearly the same number of rings, and only near the top a 

 marked diminution appears, while iu a tree sixty years old the sapwood of the stumji may liave 

 forty rings and that of a disk 40 feet from the ground only twenty- five rings. As in other pines, 

 the width of the sapwood is (juite variable and is always greatest in young and thrifty trees. 



When green the wood of this species is too heavy to float well; its weight varies chiefly with 

 the amount of sapwood, and is therefore greatest in sapling timber. The sapwood itself is 

 frequently heavier than water, and where the water in the sapwood and a large amount of 

 resin in the heartwood combine, the weight of the entire disk frequently approaches 60 pounds to 

 the cubic foot. 



Kiln-dried, the wood of trees one hundred to one hundred and fifty years old was found on an 

 average to weigh about 39 pounds per cubic foot, thus excelling in weight even the valuable Long- 

 leaf Pine. The wood of very young trees is decidedly lighter, as is also that of very old trees, 

 the heaviest wood being formed during the age of thriftiest growth or between the twentieth and 

 eightieth year. The presence of resin in the heartwood, as conspicuous in this species as in Long- 

 leaf Pine, materially adds to the weight of the wood, so that the heartwood of old trees is invari- 

 ably heavier than the same wood had been while in a sapwood condition. As in other pines, the 

 butt is heaviest and the toplog lightest; thus in trees over one hundred and fifty years of age the 

 wood at the butt weighs 44 pounds per cubic foot, 37 pounds at 38 feet, and only 32 pounds at 00 

 feet from the stump, a difference amounting to over 25 jier cent. This difl'erence is greatest in the 

 young sapling and is remarkably uniform for all adult trees examined. 



In strength, as in weight, the wood of Cuban Pine excels. The following figures represent the 

 general average of a long series of experiments on wood especially collected: 



Lbs. per sq. inch. 



Modulus of elasticity 2, 300, 000 



Transverse strength 11, 900 



Compression endwise 7, 850 



Slieariug 680 



Tension 14,300 



The average weight of the pieces tested was 49 pounds per cubic foot, the outer lighter part 

 of the old trees having largely been cut away iu shaping the pieces, so that only lieavy wood had 

 been tested. The above figures require, therefore, a reduction of about 20 per cent to represent 

 the true average strength of all the wood of entire trees. 



The amount of water contained in the fresh wood depends on the proportion of sapwood. In 

 this latter it forms about 00 per cent of the weight of fresh wood; in the heartwood onlj' about 20 

 per cent. Accordingly, fresh logs of sapling timber seventy years old have about 45 per cent, logs 

 of trees over one hundred and fifty years old only about 30 per cent of water. The wood dries 

 easily and without great injury, even if seasoned iu the dry kiln. 



