HEMLOCK
(Tsuga Canadensis)

Seven hemlocks are known in the world, four of them in America. Two of these are in the East, two in the West. The eastern species are the Canadian and Carolinian. The former is Tsuga canadensis, the latter Tsuga caroliniana. The western species are, mountain hemlock (Tsuga mertensiana), and western hemlock (Tsuga heterophylla). The word tsuga is Japanese and means hemlock.

The hemlock lumber in eastern markets is practically all from one species, which is known as hemlock in Maine, New Hampshire, Vermont, Massachusetts, Rhode Island, Connecticut, New York, New Jersey, Pennsylvania, Delaware, Virginia, North Carolina, South Carolina, Kentucky, Wisconsin, Michigan, Minnesota, Ohio, Ontario. In Vermont, Rhode Island, New York, Pennsylvania, New Jersey, West Virginia, North Carolina, South Carolina; in England it is called hemlock spruce; spruce tree in Pennsylvania and West Virginia; spruce pine in Pennsylvania, Delaware, Virginia, North Carolina, Georgia; to the New York Indians it was known as oh-neh-tah, which being interpreted means “greens on the stick.”

The range of hemlock extends east and west more than fifteen hundred miles, from Nova Scotia to western Wisconsin; south to Delaware and southern Michigan, and along the Appalachian mountains to northern Alabama and Georgia. The original quantity of timber was enormous, for large areas were covered with dense stands. The largest trees are found near the southern part of its range, among the mountains of Tennessee and North Carolina; but the bulk of the timber has always been in the North. It thrives best in well drained soil, but it likes cool situations and often develops dense forests on northern slopes or in deep ravines; but it maintains a foothold on ridges, on the banks of streams, and around the borders of swamps.

The cones are very small, about a half inch in length, growing singly from the lower side of the branchlet. Their scales are rounded and thin, light brown in color. The seeds are winged and even when ripe the cones do not spread apart perceptibly. The seeds escape, however, slowly during the winter following their maturity. They are very small, and their wings distribute them a hundred feet or more. The seeds germinate best on leaf mold, but the seedling takes several years to thrust its roots deep into the mineral soil. During that time, growth is very slow. A seedling five years old may not exceed five inches in height; but when its roots have developed, growth is fairly rapid. The distribution of seeds is often facilitated by the activities of red squirrels, and perhaps other small mammals, which climb the trees in winter and tear the cones apart to get at the seeds. Many of the seeds are devoured, but more escape and fly away on the winter winds.

Hemlock leaves are narrow and about half an inch long. Examined closely, particularly with a magnifying glass, rows of white dots extend from end to end on the under side. Small as these white points are separately, when seen in the aggregate they change the color of the whole crown of the tree. This is illustrated by looking at a hemlock from a distance—the upper sides of the leaves on the drooping twigs being then visible and the tree’s aspect dark green. Approach the tree, and look up from its base—the under side of the leaves being then visible—and the dark color changes to a light silvery tint. The whiteness is due to the white spots on the leaves. The spots are stomata (mouths), and are parts of the chemical laboratory which carries on the tree’s living processes. All tree leaves have stomata, but all are not arranged in the same way and are not visible alike. Few trees have them as prominent as the hemlocks.

Hemlock attains a height from sixty to 100 feet and a diameter from two to four. When it grows in the open, it is one of the handsomest and most symmetrical evergreens of any country. Its dark, dense foliage will permit scarcely any sunlight to filter through. When forest-grown, it loses its lower limbs. In the forester’s language, they are “shaded off,” and long, smooth trunks are developed; but the stubs from which the branches fall remain buried deep inside the smoothest bole, and the saws will find them when the logs are converted into lumber.

Reference has been made to hemlock’s slow growth during the seedling’s first four or five years. That takes place in the dense shade of the hemlock forest. If the seed falls on open ground, in full sunlight, the chance is that it will not germinate; but if it does, the seedling is doomed to an early death. It cannot endure strong light. This fact is of great importance, for it means the end of hemlock forests. When a stand is cut and the sunshine reaches the ground, no seedlings bring on a new forest. White pine seeds grow in open ground, in old fields, in burnt woods, wherever they reach soil, but hemlock must scatter its seeds in cool, deep shade or they will do little good. Strong, vigorous, and healthy as hemlock trees are, they are killed more easily than almost any other. Cut a few trees from the center of a mature hemlock clump, and the chance is that several trees next to the open space thus made will die. The unusual light proves too much for their roots which had always been cool and damp; but when young hemlocks are protected until they get a start, they thrive nicely in the open.

The wood of hemlock is light, soft, not strong, brittle, coarse and crooked grained, difficult to work, liable to windshake, splinters badly, not durable. The summerwood of the annual ring is conspicuous; and the thin medullary rays are numerous. The color of hemlock heartwood is light brown, tinged with red, often nearly white. The sapwood is darker. Lumbermen recognize two varieties, red and white, but botanists do not recognize them.

The physical characters of hemlock are nearly all unfavorable, yet it has become a useful and widely used wood. It is largely manufactured into coarse lumber and used for outside work—railway ties, joists, rafters, sheathing, plank walks, laths, etc. It is rarely used for inside finishing, owing to its brittle and splintery character. Clean boards made into panels or similar work and finished in the natural color often present a very handsome appearance, owing to the peculiar pinkish tint of the wood, ripening and improving with age.

With the growing scarcity of white and Norway pine, hemlock has become the natural substitute for these woods for many purposes. It has never been conceded that hemlock possesses the intrinsic merit of either of the northern pines for structural purposes, but it has proven a suitable substitute for a variety of uses, notably for framing and sheathing of medium priced structures.

In 1910 hemlock lumber was cut in twenty-one states, the total output exceeding 2,500,000,000 feet. Only four species or groups of species exceeded it in amount. They were southern yellow pines, Douglas fir, the oaks, and white pine. The principal cut of hemlock lumber was in the following states in the order named: Wisconsin, Michigan, Pennsylvania, West Virginia, New York, Maine, Vermont, Virginia, New Hampshire, Tennessee, and North Carolina. Ten other states produced smaller amounts.

Hemlock possesses remarkable holding power on nails and spikes, and that is one reason for its large use for railroad ties. It does not easily split, and there is no likelihood that spikes will work loose; but the wood decays quickly in damp situations, and unless given preservative treatment, hemlock ties do not last long. They are pretty soft anyway, and where traffic is heavy, rails cut them badly.

Manufacturers of boxes and crates use much hemlock. The annual use for that purpose in Massachusetts is about 27,000,000 feet, in Michigan practically the same quantity, in Illinois 34,000,000, and varying quantities in many other states. Michigan converts nearly 100,000,000 feet a year into flooring and other planing mill products, and Wisconsin and other hemlock states follow it in lesser amounts. The wood is employed by car builders, slack coopers, manufacturers of refrigerators, silos, and farm implements; but the largest demand comes from those who use the rough lumber.

Hemlock bark is the most important tanning material in this country. It has long been used by leather makers who generally mix it with some other bark or extract because leather tanned with hemlock alone has a redder color than is desired.

Large areas of hemlock forests have been cut for the bark alone. Formerly the wood was of so little value that it was cheaper to leave it in the forest than to take it out. The peelers worked in early summer, cutting trees and removing the bark in four-foot lengths, which was measured by the cord, though often sold by weight. Care was taken that the bark be removed from the slashings before the dry weather of autumn, for fire was to be expected then, and anything combustible in the woods at that time was likely to be lost. The tracts on which bark peelers worked were called “slashings,” and they were fire traps of the worst kind with their tangled masses of tops and branches.

Large quantities of hemlock bark are still peeled every summer, but the practice is less destructive than formerly. The trunks are worth taking out, and when the fire comes late in the season it consumes little valuable hemlock. A permanent decline in the annual production of this wood has not yet begun, but it must soon set in, for the demand cannot be indefinitely met.