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the loblolly and longleaf pine. Wherever in these upland forests an opening is made the shortleaf pine gains over its associates, finding its only successful rival in the loblolly pine. It is in the Southern States proverbial that in the upland forests "the pine is crowding out the hard-wood timber," a fact early observed. The displacement is effected either gradually in the course of time, or instantly when the removal of the original timber growth has been sudden. In the upper part of the maritime pine belt, where it is associated with the longleaf pine, the latter is sure to be replaced by the shortleaf species, often joined in the course of such invasion by the loblolly pine.

LOBLOLLY PINE.

The crops of seed are produced quite abundantly every year and copiously dispersed over the vicinity of the mother trees by the wind, the offspring quickly taking possession of old fields and clearings in the forest.

The seeds germinate in the early spring. The ends of the cotyledons remain for a short time after germination inclosed in the endosperm. The number of the germinal leaves (cotyledons) is mostly six, rarely seven. At the time of the unfolding of the cotyledons the lower (hypocotyledonary) part of the axis of the plant is about 1 inch in length. The rootlets are half that length, and are provided with several acropetal secondary rootlets. The caulicle grows rapidly, and is soon covered with the stiff, needle shaped, and strongly serrulated primary leaves. Before the spring season has passed the bundles of secondary or foliage leaves make their appearance in the axils of the former. At the close of the summer season the plantlet has attained a height of from 6 to 8 inches, the upper part of the stem covered with foliage leaves, the acerose primary leaves of the lower part having completely withered. In examining a large number of young plants never less than three leaves in a bundle have been found during this or any subsequent stage of the growth. With the second year the primary leaves have all become reduced to the ordinary form of the leaf bract-lanceolate, acuminate, with fimbriate white hyaline edges and tips. In all the specimens examined it was found that the growth of the main axis proceeded less rapidly during the second season, but produced a regular whorl of from three to four lateral axes. At the close of the second year the main stem rarely exceeds 10 inches in height.

At the end of their third year the plants are from 18 to 20 inches high, the stem being from one-fourth to five-sixteenths of an inch in thickness. The branches, forming regular whorls, are erect and produce in their turn whorls of secondary order. The root system shows a corresponding increase, the taproot being from 6 to 8 inches long, with numerous stout lateral roots.

With the fourth year the loblolly pine enters seemingly upon the period of quickest growth. As ascertained by many measurements, the trees at the end of their fourth year average 3 feet in height and from one-half to seven-eighths of an inch in diameter, and at the end of the fifth year measure nearly 5 feet and from 1 to 14 inches in diameter. At the beginning of the seventh year the tree attains a height of 10 feet, and with the close of the first decade trees are found 12 to 16 feet high and from 23 to 3 inches in diameter. Some trees begin to mature their first cones by the tenth year.

The above measurements were made in 1890 in the vicinity of Cullman, Ala., on trees taken indiscriminately from the midst and near the border of a dense pine thicket covering a field plowed for the last time in 1882, and from an adjoining opening in the forest protected from fire and but rarely used for pasture.

According to a number of measurements made of trees in the southern Atlantic States, the Gulf region, and southern Arkansas, the loblolly pine reaches at the tenth year, on the average, a height of 20 feet, doubling this height during the succeeding decade. During this period of quickest growth the increase in height proceeds at the rate of 2 feet per annum, and trees twenty years old average 44 inches in diameter breast high. At the age of fifty years the trees are from 65 to 75 feet in height (average about 70 feet) and 15 inches in diameter breast high. The annual increase for this period of thirty years is about 1 foot in height and 0.35 inch in diameter. From numerous observations it appears that the loblolly pine attains the fullness of its growth at the age of one hundred years, with a height, on the average, of 110 feet and a diameter breast high of 2 feet, the length of merchantable timber varying between 50 and 60 feet. The annual rate of height growth during the second half century is about eight-tenths of a foot, and the diameter H. Doc. 181—6

growth eighteen one-hundredths of an inch. Henceforth the growth in height remains almost stationary. A dozen trees from one hundred to one hundred and fifty years old were found to vary from 99 to 125 feet in height, with a length of trunk free from limbs of from 60 to 68 feet and from 19 to 27 inches in diameter at breast height.

From tabulated records of growth it becomes evident that under similar conditions of soil and exposure the rate of increase for the various stages of growth show but slight differences in localities widely distant from each other.

Soil and climate.-The loblolly pine prefers a moist, cool, sandy, or light loamy soil, which if not always moist, should have greater retentiveness for moisture than is required by most of the other upland pines. It reaches its greatest perfection in the perpetually moist or fresh forest lands with a soil of a sandy loam, rich in vegetable mold which border the swamps of the coast region. The tree is not found on the porous highly silicious soils of the more elevated uplands, where the longleaf pine almost exclusively prevails. It also avoids heavy clay and calcareous soils of the uplands and the alluvial lands.

The loblolly pine is a tree of austral regions confined to the humid belt of the austro riparian or Louisianian zone and the lower border of the Carolinian life zone, which on the Atlantic coast follows quite closely the isothermal line of 56 F.; westward, in the direction of the Gulf coast, the isothermal line of 60. The mean temperature of the winter along the northern limit is about 450, with the lowest temperature only occasionally falling below 10° F. This tree approaches the Appalachian zone only under the influence of a peninsular clime between the Delaware and Chesapeake bays.

The loblolly appears to be indifferent to the wide differences in the amount of atmospheric precipitation existing within the vast range of its distribution. Extending from Florida (isotherm, 70) to the thirty-ninth degree of north latitude on the Atlantic coast (isotherm, 562), it is found of equal thrift on the Gulf shore, with its damp air and annual rainfall exceeding 64 inches, and in the flat woods of Texas, where the mean annual precipitation is only one-half that amount, with a mean of 6 inches during the winter months. In fact, the loblolly pine is found most frequently and is more widely distributed in the districts of lesser precipitation. It is certainly more dependent on the supplies of soil moisture than upon atmospheric humidity.

Relation to light and associated species.-This species is less exacting in its demands for direct sunlight than the kindred species within its range. To this relation may be ascribed the success which it achieves in the struggle for the possession of the soil with the shortleaf pine. Observing this contest as it is going on between the competing species in the forest, the conditions of the soil being equally favorable, the loblolly pine, under the cover of shade, outstrips the shortleaf pine under the same conditions; and, on the other hand, where the sunlight has had unhindered access, it gives way to its competitor, being then subjected to the disadvantage resulting from a speedier desiccation of the soil. Through such influences it is that, under conditions seemingly equally favorable to either one of these pines, now the one and now the other is found to predominate.

In the deep forests covering the rich swampy lands of the coast regions, the loblolly pine forms comparatively a small part of the rich and varied growth consisting chiefly of deciduous trees, black gum, sweet or red gum, water oak, and mockernut, to which in the lower South the magnolia, sweet bay, red bay, and Cuban pine are to be added. Although requiring less sunlight than most pines, in the gloomy impenetrable shade of these dense forests the progeny of the loblolly pine has no future, especially as these lands once cleared are devoted to tillage, being of great agricultural value.

On the lands of a poorer, more exposed soil in the maritime plain of the southern Atlantic States, in Virginia and North Carolina, and in southwestern Texas, this pine forms more or less compact forests. In these forests the tree is always succeeded by its own progeny, either in the course of nature or after the artificial removal of the original forest growth. On the coast of Georgia, in Florida, and in the coast plain of the eastern Gulf States, the loblolly pine is scattered among the Cuban and the longleaf pine; there its second growth meets a formidable competitor in the first named of these species. In the flat woods, deprived of drainage, the Cuban pine is always found to vastly outnumber the loblolly among the young forest growth. In the upper part of the great maritime pine belt the loblolly pine is frequently found among the mixed growth of magnolia, Spanish, red, post, and blackjack oaks, mockernut and pignut hickory, shortleaf pine,

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II. Doc. 181.

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LOBLOLLY PINE (PINUS TÆDA L.).

Q.HEIDEMAN.Sc.

a, aments of female flowers; b, immature cone, one season's growth; c, mature cone; d, open cone; e, f, cone scales, outer and inner side: g, seed and wing.

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