of their age. As far as could be observed the growth proceeds equally slowly during the fifth and sixth years, the plant at the end of that period being from 5 to 7 or 74 inches in length. Stage of rapid growth. With its seventh year the tree may be said to enter on its most vigorous growth. Henceforth the stem (primary axis) increases rapidly in length, and the development of branches (lateral axes) proceeds at an equal rate in regular whorls, to which the symmetry of the tree in that stage of its development is due. During the seventh year, generally, the tree doubles its length, and during a number of successive years the rate of growth in that direction varies between 10 and 20 inches annually, as is clearly shown by the length of the internodes separating the whorls. As the branches increase in length they produce, in the same order mostly, two opposite secondary branches. With the rapid expansion of the leaf surface, the formation of wood keeps pace. The rate of growth in diameter, as well as in height, during this period is, of course, variable according to differences in the physical condition of the soil, as well as in the available amount of plant food and moisture it contains, and no less upon differences in temperature and of exposure to light and air. When the tree has reached its second decade it begins to produce flowers and fruit. Having during the course of the following fifteen years reached a length of from 40 to 45 feet, with the main stem clear of limbs, the growth of branches does not proceed with the same regularity; consequently they are no longer arranged in regular whorls, but appear irregularly, and thus the symmetry of the tree is lost. Stage of slow growth.-Rapid as is the increase in length of the primary axis or trunk, amounting during the first half century, in the average, to 14 or 15 inches annually, the rate is subsequently greatly diminished, averaging from the fiftieth to about the one hundred and fifteenth year but from 4 to 5 inches, and from this time to the age of two hundred and fifty years only 14 inches—that is, at a relative rate of 10, 3, and 1 in the three successive periods. The decrease in the accretion of wood corresponds with the reduction in the growth of the branches and consequent reduction of foliage. From what has been said, it is seen that the longleaf pine attains maturity of growth, with the best qualities of its timber, at an age of from one hundred and eighty to two hundred years. After having passed the second century the trees are found frequently to be wind shaken and otherwise defective. The deterioration of the weather beaten crown lessens the vitality of the tree, and the soil, under prevailing conditions, becomes less and less favorable. In consequence, the trees become liable to disease and mostly fall prey to the attacks of parasitic fungi (red heart). Instances of trees which have reached the maximum age of two hundred and seventy-five or three hundred years are exceptional. In order to ascertain the age required to furnish merchantable timber of first quality, measurements were made of a number of logs in a log camp in the rolling pine uplands of the lower division of the coastal pine belt near Lumberton, Washington County, Ala. From the results obtained it appears that in this section of the eastern Gulf region, at the lowest figure, two hundred years are requisite to produce logs of the dimensions at present cut at the sawmills. Demands upon soil and climate.—In its demands upon the soil this pine is to be counted among the most frugal, as far as mineral constituents, which are considered as plant food, are concerned, if only the mechanical conditions which influence favorable soil moisture are not wanting. It thrives best on a light siliceous soil, loamy sand or pebbles or light sandy loam, with a slightly clayey subsoil sufficiently porous to insure at least a partial underdrainage and to permit unimpeded development of the long taproot. Whenever the tree meets an obstacle to the development of this root it remains more or less stunted. The luxuriance of the growth and increase in size of the timber, however, is greatly influ enced by the quantity of clay present, particularly in the deep subsoil, which improves mechanical and moisture conditions. This is strikingly exhibited in the timber of the level pine flats west of the Mississippi River, although the surface drainage is almost wanting and the underdrainage through the loamy strata slow, so that the surface of the soil remains damp or water-soaked for the greater part of the year; the stand of timber of first-class dimensions exceeds considerably that of the rolling pine uplands on the Atlantic slope and the lower part of the pine belt in the eastern Gulf region, which are poorer in clay. Evidently, although the underdrainage is less perfect, the moisture conditions during the dry season of the year, the time of most active growth, must be most favorable. The same fact is apparent in the upper part of the coast pine belt in Alabama and Mississippi, where, upon the same area, with a smaller number of trees, the crop of timber may be considered almost twice as heavy as that found on the pine barrens proper farther south. On the soil of fine, closely compacted sand, entirely deficient in drainage as found in the so-called pine meadows along the coast of western Florida, Alabama, and Mississippi, as well as on the siliceous rocky ridges of central and northern Alabama, the tree is so stunted as to be of little or no value for its timber. "It is neither temperature alone, nor rainfall and moisture conditions of the atmosphere alone, that influence tree growth, but the relation of these two climatic factors, which determines the amount of transpiration to be performed by the foliage, and again with most species we must place this transpiration movement into relation with available soil moisture, in order to determine what the requirements and the most suitable habitat of the species are" (B. E. Fernow). Hence we find that east of the Mississippi River the longleaf pine occurs in greatest frequency along the isotherm of 60° F. ranging to 34 north latitude, while west of the Mississippi it follows a line between the isotherms of 63 and 64° F. and is scarcely found north of the thirty-second parallel of north latitude. Within this area of its distribution it is exposed to wide variation of temperature and moisture conditions. Under the influence of the vapor-laden breezes from the Mexican Gulf and an evenly dis tributed rainfall ranging from 42 to 63 inches during the year, the longleaf pine appears of the same thrift and vigor of growth in the interior of Alabama under 31° to 35° north latitude, with the thermometer falling as low as 4° F. (16o C.) and a range of temperature of 93° (at Tuscaloosa), as it is found in the subtropical belt of the coast with a maximum temperature of 105° F. (40° C.) and a range of temperature of 94 west of the Mississippi River, although the temperature reaches rarely a minimum of 15 and 129, respectively, at the northern limit of the tree in these States, the diminished humidity of the atmosphere and lesser rainfall, particularly during the warmer season, account for its absence. There can be no doubt that the greater exposure to the violence of the sudden gusts of dry and cold wind known in Texas as "dry northers" exercises also no small influence in limiting the longleaf pine. Associated species.-The longleaf pine is eminently a gregarious tree, covering areas of wide extent, to the almost complete exclusion of any other species. In the flat woods of the coastal plain, particularly near its northern limit on the Atlantic slope, it is not infrequently associated with the loblolly pine; farther south and along the Gulf coast to the Mississippi River, more or less frequently with this tree and the Cuban pine. In the upper part of the maritime pine belt it not rarely occurs together with the shortleaf pine and the loblolly pine intermixed with the deciduous trees of the uplands, viz, the black oak, Spanish oak, black jack, bitternut, mockernut hickories, and black gum. It will be apparent, from what has been said regarding the demands for light, that the associated species must be either slower growers or later comers, if the longleaf pine is to survive in the mixture. As has been pointed out elsewhere, with the culling of the longleaf pine from the mixed growths it must soon cease to play a part in them, since its renewal under the shade of the remaining associates is impossible. Enemies.-The greatest danger threatening the existence of the forests of longleaf pine must be ascribed to the agency of man, since their destruction is caused chiefly by the reckless manuer in which they are depleted without heed to recuperation. The right of ownership has been generally acquired on such low terms that since no value has been attached to the land without the timber, despoliation has been carried on with no other object than the quickest return of pecuniary profits. Exploitation. Such management could not but entail tremendous waste, a large percentage of the body of the trees felled being left on the ground to rot or to serve as fuel for the conflagrations which scour these woods almost every year. Infinitely greater than the injuries inflicted upon the forest by the logger and by getting out cross-ties and hewn square timber, which consist chiefly in the accumulation of combustible waste, are those caused by the production of naval stores. When the fact is considered that the production of the 40,000 barrels of spirits of turpentine, which on an average during the latter half of this decade annually reached the market of Mobile alone, implies the devastation of about 70,000 acres of virgin forest, the destruction caused by this industry appears in its full enormity. Under the management of the turpentine orchards H. Doc. 181. a, branch with terminal bud; b, leaf bundle: c, d, primary leaf bracts (magnified); e, cross section through base of leaf bundle (magnified); f, g, cross sections (magnified) of leaves; h, longitudinal section through leaf. |