98 TIMBER PINES OF THE SOUTHERN UNITED STATES. 



As the average weight of this series was 3S pounds pec cubic foot, or about Ifi jjer cent heavier 

 than the average weight involving all parts of all the trees, these figures should be reduced by 

 that per cent to rejjresent the true average for the wood of the species. 



In drying, 100 pounds of wood lose from 40 to 50 pounds of water, the bulk of which comes 

 from the sapwood, which contains GO per cent and more, while the heartwood, like that of most 

 pines, contains about 25 per cent. 



The shrinkage in volume consequent on drying amounts to about 11 per cent. It is about 13 

 per cent in the wood of the butt and about 10 per cent in that of the upper logs, varying in this 

 respect directly as the weight of the dry wooa. Of the 11 per cent, about 8 per cent fall to the 

 tangent or occur along the rings and 3 to 5 per cent along the radius. 



The structure of the wood of Shortleaf Pine is essentially the same as that of Loblolly. Sum- 

 merwood and springwood are sharply defined. The proportion of the former to the wood on tlie 

 whole varies, as in I>oblolly, in the same manner as the weight of the wood, being greater in tlie 

 butt than top, greater in the wood of the inner rings than in the wood farther out, and greatly 

 reduced in all cases where the growth of the tree is suddenly retarded by unfavorable seasons, 

 but is otherwise (piite independent of the width of the rings. 



For details of structure, consult the comparative study of Mr. Eoth, appended to these 

 monographs. 



PROGRESS OF DEVELOPJVIENT. 



The seeds begin to swell and to germinate in the early days of spring. In Mobile County, ou 

 the end of the first week of ^larch, the plantlets had their cotyledons fully unfolded, which were 

 found to vary from six to seven in number, with the lower (hypocotyledonary) part of the axis from 

 li to 2 inches long, the rootlets being somewhat less in length (PI. XV, c,g). The development 

 of the upper part of the axis (caulicle) from the terminal budlet and of the primary acerose leaves 

 proceeds now rapidly. These primary leaves succeeding the cotyledons are stiff and spreading, 

 about three-fourths of an inch long and covering the stem densely (PI. XV, (j), remain during the 

 first season, withering from below during the warmer part of the season. By the close of the first 

 season the caulicle or first shoot has attaineti a length of from 3 to 4 inches. On the shoot of 

 the second season (rarely biifore) the secondary leaves, which constitute the foliage, make their 

 appearance from the undeveloped branchlets in the axis of the primary leaves (PI. XY, g). At 

 the end of the second year the plants are 7 to 8 inches high, with a taproot 2 to 3 inches 

 long. During tins season adventitious buds appear at the collar of the stem, which bring forth 

 vigorous sprouts, particularly if the stem has sustained the slightest injury. These shoots are 

 covered with primary heaves, which are retained for one season. They are apt to form strong 

 brandies before the tree has reached its fourth or fifth year; such branches, which are produced 

 profusely from the stumps of larger trees, scai'cely survive another season. Jt is rarely that 

 branches are produced in the second year, the first branches appearing generally in the third 

 season in whorls of three to four. In the third year foliage leaves alone are produced in the axils 

 of scales with their bases close to the stem. At the close of the third year tlie plants are from 12 

 to 18 inches high. Now the development of the root system advances rapidly, the taproot being 

 by this time about 8 or 10 inches long, with strong lateral roots often double that length. Both 

 taproot and lateral roots arc liiially vigorously developed, penetrating deej) into the ground, so 

 that trees of this species are rarely blown down by winds. At the end of the fourth year the 

 plants are from 2 to 3 feet high, with the stem at best from five-eighths to seven-eighths of au 

 inch thick. 



The branches of the whorls begin now in their turn to develop l)ranchl('ts in w horls of secondary 

 order. The development of the primary axis and its branch system proceeds henceforth in the 

 regular acropetal order. As in all pines, the shoot of the main axis takes the lead in rapidity and 

 vigor of growth. By a number of measurements made at Cullman, north .Vlabama, of trees from 

 the ojjenings in the forest, as well as from clearings, it was found that by the end of the fifth year 

 they had attainetl a height varying between 3 and 5 feet, rarely over, the stem being from five-eighths 

 to seven-eighths of an inch in thickness; by the end of the sixth year, from to 9 feet high and 

 from one-half to 2 inches in diameter; and at the tenth year, from 10 to 10 feet high and liom 2 



