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Key to Species — Part 6

A. Leaves flat, 2-ranked, pale beneath; cones about 1 inch long, oval.

B. Cones stalked.

C. Scales as wide as long, not flaring at maturity. (T. Canadensis) HEMLOCK

CC. Scales longer than wide, flaring at maturity. (T. Caroliniana) CAROLINA HEMLOCK

BB. Cones sessile, scales constricted in middle. (T. heterophylla) WESTERN HEMLOCK

AA. Leaves 3-angled, whorled, pale blue-green; cones 2 to 3 inches long, oblong-cylindrical. (T. Mertensiana) MOUNTAIN HEMLOCK

Hemlocks are distinctly graceful and symmetrical trees. Japan has two native species, the Himalayas one, our Eastern States one, the Western States three--seven in all--and Tsuga is the Japanese name for hemlock. The prostrate, shrubby "ground hemlock," familiar to many of us who have eaten its aromatic scarlet berry, is not a hemlock but a yew. The hemlock that Socrates drank was the deadly infusion of an herb, Conium maculatum, related to our wild carrot.

The best character by which to recognise the hemlocks is the tiny petiole of the leaf. No other cone bearer has leaf stalks. Of our native species, all have white lines on the under side of each leaf; the mountain hemlock has them above and below. The first three species have leaves 2-ranked and flat and cones under an inch in length; the fourth has leaves 3-angled, whorled on the twigs, and cones 2 to 3 inches long. Cones are pendant, and thin scaled in all the species, and are borne annually.

Hemlocks are important ornamental trees. They come readily from seed, if shaded, and transplant safely, owing to their dense fibrous root system. They submit to serve pruning of roots or tops. They are not particular in regard to soil, if only it be moist. The two Japanese species are propagated from cuttings, or are grafted on our Eastern hemlock. All hemlocks have bark rich in tannin. The west American species are all large trees, except at high altitudes.

Hemlock (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.