104 TIMBER PINES OF THE SOUTHERN UNITED STATES. 



As the average weight of this series was 38 pounds per cubic foot, or about 16 per cent lieavier 

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

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



In drying, 100 pounds of wood lose from 40 to oO pounds of water, the bulk of which conies 

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

 pines, contains about 25 per cent. 



The shrinkage in volume consecjuent 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 u])per logs, varying in this 

 respect directly as the weight of the dry wood. 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 the 

 whole varies, as in JiobloUy, in the same manner as the weight of the wood, being greater in the 

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

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

 but is otherwise quite independent of the width of the rings. 



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

 monographs. 



PROGRESS OF DEVELOPMENT. 



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

 the end of the first week of March, 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 inche.s long, the rootlets being somewhat less in length (PI. XV, e, ;/). The development 

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

 proceeds now i-apidly. The.se primary leaves succeeding the cotyledons are stiff and spreading, 

 about three-fourths of an inch long and covering the stem den.sely (PI. XV^, (/), 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 attained a length of from 3 to 4 inches. On the shoot of 

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

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

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

 During this 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 leaves, which are retained for one season. They are apt to form strong branches 

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

 from the stumps of larger trees, scarcely survive another season. It is rarely that branches 

 are produced in the second year, the first branches appearing generally in the thii'd 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 the plants are from 12 to 18 

 inches high. Xow 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 are finally vigorously developed, penetrating deep 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 

 an inch thick. 



The branches of the whorls begin now in their turn to develop branchlets in whorls 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 Alabama, of trees from 

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

 they had attained 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 eiid of the sixth year, from to 9 feet high and 

 from one-half to 2 inches in d'ameter; and at the tenth year, from 10 to 10 feet high and from 2 



