Plant Guide > Trees > Hemlocks > Hemlock Tree

Hemlock Tree

Hemlock TreeHemlock (Tsuga Canadensis, Carr.)-A broadly pyramidal tree, 60 to 100 feet high, with tapering leading shoot and pendulous horizontal limbs. Bark cinnamon red to grey, thin, furrowed, scaly. Wood light, soft, coarse, cross-grained, not durable. Buds small, obtuse. Leaves flat, blunt, pale beneath, dark, shining above, on short petioles jointed to projecting bases, 2-ranked, shed in third year. Flowers in May, monoecious, solitary; pistillate terminal on short shoots. Fruit small, annual cones, falling in spring, oval, thin scaled, red-brown, turning to grey. Preferred habitat, rocky uplands near streams. Distribution, Nova Scotia to southern Michigan, central Wisconsin and Minnesota; southward to Delaware, and along Appalachian Mountains to Alabama. Uses: Wood, in building and for railroad ties; bark, in dyeing and in tanning leather. Cultivated as an ornamental tree and hedge plant.

" Hemlock Hill" in the Arnold Arboretum is a shrine at which the true tree-loving Bostonian worships at least once a year. It is a remnant of the forest primeval that clothes a steep promontory just inside one of the gates. In winter the hemlocks look black in contrast with the snow that hides the paths and smothers the brook into silence. It is awesome-this solitude of winter on the hill. But in summer all is different. The severity of its winter aspect is gone. Every twig waves in welcome a yellow-green plume, the new growth of the year, and up the hillside climb the well-remembered paths. The brook goes singing along between borders of laurel and rhododendron. The gloom of the hemlocks is wonderfully lightened, when one is actually under them, by the pale linings of the individual leaves, just two parallel lines of white on each narrow blade, but the aggregate makes a mighty difference in the atmosphere of the place.

Throughout New England one finds generous appreciation of this native hemlock. The slender terminal shoot, "the leader," lifted into the sky is a weather vane that never gets out of order. Where hemlocks of considerable size are scattered among pines or other trees, they are guideposts to the "timber cruiser" or the hunter in trackless woods. Each treetop has its own individuality -the scars of storms outridden, or other modifying influences at work.

The specimens of hemlock to be seen in parks and on private grounds exhibit the fitness of this species for ornamental planting. The symmetry and grace of the "dark green layers of shade," spreading into intricate sprays of remarkable delicacy, are familiar in forest and lawn. The pale bloom on the under sides of the leaves is punctuated by the little violet cones, pendant from every spray. There are many horticultural forms of this species, but, to my mind, none are as handsome as the wild species.

In winter the red squirrel finds a stable base of supplies in every fruitful hemlock tree. The litter of cone scales on the snow will convince any doubter, if, indeed, the squirrel does not himself appear and scold the intruder.

In hedges the young trees are thrifty, and even the shears cannot subdue the grace that renews every spring the delicate, flexible new shoots. They seem more like wavering tendrils of a vine than branches of a sturdy conifer.

The seeds of hemlock are slow to germinate on burned-over ground, but in the leaf mould, overshadowed by larger trees, they start in great numbers. For four or five years they average scarcely an inch a year, but they produce a good root system. After this they rapidly mount upward to independence. They supply a valuable protective cover for seedling white pines. The two species grow together often in large forests. Canada offers the best soil and climate for hemlock. It requires cool air with rich, loamy soil, moist but well drained. It is found plentifully in our Northern and Eastern States, and follows the mountains to Alabama.

Hemlock wood is coarse and splintery, likely to be crossgrained and full of knots. It warps in seasoning, and wears rough; moreover, it is brittle and weak. It has two cardinal virtues that adapt it for railroad ties and the large beams used in the frames of houses and barns. Hemlock timbers are stiff, and the wood has a firm grip on nails and spikes. The wood never loosens its hold upon the nail, nor does it split in nailing. Hemlock is used for the outside of cheap buildings, but it finds its greatest usefulness as the unseen props of a house, its faults covered up by woods of more uniform and attractive appearance.

The bark of hemlock abounds in tannin, which makes it a standard tan bark. It is not uncommon to see young hemlock woods felled and stripped for the bark alone. The waste of the wood is very bad forestry, but as hemlock is poor fuel, and ugly to saw and split, sometimes cordwood costs more to cut and haul than it brings in market. If the trees were left to attain proper age for mill stuff, the lumber would be salable, and there would be a much larger crop of bark.

The logs are cut for tan bark only in the summer. The bark "slips" from May until August. After that, peeling is impossible. The logs are girdled every four feet from the butt well up into the tops. Two or three cuts are made at equal distances apart, lengthwise of the trunk. This makes of each four-foot cylinder of bark two or three rectangular sheets, easily removed with a special bark-peeling tool. The sheets are stacked on end to dry, and are later laid in solid four-foot piles to be measured by the cord. The hemlock bark is usually mixed with some oak bark at the tanneries. A side of sole leather tanned with hemlock alone is a brighter red than is desired. The oak darkens it. Dye works consume some hemlock bark in making certain shades of brown.

Oil of hemlock is distilled from the leaves. "Canada pitch," formerly much used as a drug, is extracted from leaves and knots. In the practice of the Indians, the bark of young hemlocks, boiled and pounded to a paste, made a poultice for sores and wounds. Josselyn noted also: "The turpentine thereof is singularly good to heal wounds and to draw out the malice of any Ach, rubbing the place therewith." The antiseptic action of the oil and resin was recognised then as now.