4. TSUGA Carr. Hemlock.
Tall pyramidal trees, with deeply furrowed astringent bark bright cinnamon-red except on the surface, soft pale wood, nodding leading shoots, slender scattered horizontal often pendulous branches, the secondary branches three or four times irregularly pinnately ramified, with slender round glabrous or pubescent ultimate divisions, the whole forming graceful pendant masses of foliage, and minute winter-buds. Leaves flat or angular, obtuse and often emarginate or acute at apex, spirally disposed, usually appearing almost 2-ranked by the twisting of their petioles, those on the upper side of the branch then much shorter than the others, abruptly narrowed into short petioles jointed on ultimately woody persistent bases, with stomata on the lower surface; on one species not 2-ranked, and of nearly equal length, with stomata on both surfaces. Flowers solitary, the male in the axils of leaves of the previous year, globose, composed of numerous subglobose anthers, with connectives produced into short gland-like tips, the female terminal, erect, with nearly circular scales slightly longer or shorter than their membranaceous bracts. Fruit an ovoid-oblong, oval, or oblong-cylindric obtuse usually pendulous nearly sessile green or rarely purple cone becoming light or dark reddish brown, with concave suborbicular or ovate-oblong scales thin and entire on the margins, much longer than their minute bracts, persistent on the axis of the cone after the escape of the seeds. Seeds furnished with resin-vesicles, ovoid-oblong, compressed, nearly surrounded by their much longer obovate-oblong wings; outer seed-coat crustaceous, light brown, the inner membranaceous, pale chestnut-brown, and lustrous; cotyledons 3—6, much shorter than the inferior radicle.
Tsuga is confined to temperate North America, Japan, central and southwestern China, Formosa, and the Himalayas; nine species have been distinguished.
Tsuga is the Japanese name of the Hemlock-tree.
CONSPECTUS OF THE NORTH AMERICAN SPECIES.
Leaves flat, obtuse or emarginate at apex, with stomata only on the lower surface; cones ovoid, oblong or oblong-ovoid. Cones stalked. Cone-scales broad-obovate, about as wide as long, their bracts broad and truncate.1. [T. canadensis] (A). Cone-scales narrow-oval, much longer than wide, their bracts obtusely pointed.2. [T. caroliniana] (A). Cones sessile; cone-scales oval, often abruptly contracted near the middle, their bracts gradually narrowed to an obtuse point.3. [T. heterophylla] (B, F, G). Leaves convex or keeled above, bluntly pointed, with stomata on both surfaces; cones oblong-cylindric, their scales oblong-obovate, longer than broad, much longer than their acuminate short-pointed bracts.4. [T. Mertensiana] (B, F, G).
1. [Tsuga canadensis] Carr. Hemlock.
Leaves, rounded and rarely emarginate at apex, dark yellow-green, lustrous and obscurely grooved especially toward the base on the upper surface, marked on the lower surface by 5 or 6 rows of stomata on each side of the low broad midrib, ⅓′—⅔′ long, about 1/16′ wide, deciduous in their third season from dark orange-colored persistent bases. Flowers: male light yellow; female pale green, with broad bracts coarsely laciniate on the margins and shorter than their scales. Fruit on slender puberulous stalks often ¼′ long, ovoid, acute, ½′—¾′ long, with broad-obovate scales almost as wide as long, and broad truncate bracts slightly laciniate on the margins, opening and gradually losing their seeds during the winter and mostly persistent on the branches until the following spring; seeds 1/16′ long, usually with 2 or 3 large oil-vesicles, nearly half as long as their wings broad at the base and gradually tapering to the rounded apex.
A tree, usually 60°—70°, and occasionally 100° high, with a trunk 2°—4° in diameter, gradually and conspicuously tapering toward the apex, long slender horizontal or pendulous branches, persistent until overshadowed by other trees, and forming a broad-based rather obtuse pyramid, and slender light yellow-brown pubescent branchlets, growing darker during their first winter and glabrous and dark red-brown tinged with purple in their third season. Winter-buds obtuse, light chestnut-brown, slightly puberulous, about 1/16′ long. Bark ½′—¾′ thick, deeply divided into narrow rounded ridges covered with thick closely appressed scales varying from cinnamon-red to gray more or less tinged with purple. Wood light, soft, not strong, brittle, coarse-grained, difficult to work, liable to wind-shake and splinter, not durable when exposed to the air, light brown tinged with red, with thin somewhat darker sapwood; largely manufactured into coarse lumber employed for the outside finish of buildings. The astringent inner bark affords the largest part of the material used in the northeastern states and Canada in tanning leather. From the young branches oil of hemlock is distilled.
Distribution. Scattered through upland forests and often covering the northern slopes of rocky ridges and the steep rocky banks of narrow river-gorges from Nova Scotia to eastern Minnesota (Carleton County), and southward through the northern states to Newcastle County, Delaware, cliffs of Tuckahoe Creek, Queen Anne’s County, Maryland, southern Michigan, southern Indiana (bank of Back Creek near Leesville, Laurence County), southwestern Wisconsin, and along the Appalachian Mountains to northern Georgia, and in northern Alabama; most abundant and frequently an important element of the forest in New England, northern New York, and western Pennsylvania; attaining its largest size near streams on the slopes of the high mountains of North Carolina and Tennessee.
Largely cultivated with numerous seminal varieties as an ornamental tree in the northern states, and in western and central Europe.
2. [Tsuga caroliniana] Engelm. Hemlock.
Leaves retuse or often emarginate at apex, dark green, lustrous and conspicuously grooved on the upper surface, marked on the lower surface by a band of 7 or 8 rows of stomata on each side of the midrib, ⅓′—¾′ long, about 1/12′ wide, deciduous from the orange-red bases during their fifth year. Flowers: male tinged with purple; female purple, with broadly ovate bracts, scarious and erose on the margins and about as long as their scales. Fruit on short stout stalks, oblong, 1′—1½′ long, with narrow-oval scales gradually narrowed and rounded at apex, rather abruptly contracted at base into distinct stipes, thin, concave, puberulous on the outer surface, twice as long as their broad pale bracts, spreading nearly at right angles to the axis of the cone at maturity, their bracts rather longer than wide, wedge-shaped, pale, nearly truncate or slightly pointed at the broad apex; seeds ⅙′ long, with numerous small oil-vesicles on the lower side, and one quarter as long as the pale lustrous wings broad or narrow at the base and narrowed to the rounded apex.
A tree, usually 40°—50°, or occasionally 70° high, with a trunk rarely exceeding 2° in diameter, short stout often pendulous branches forming a handsome compact pyramidal head, and slender light orange-brown pubescent branchlets, usually becoming glabrous and dull brown more or less tinged with orange during their third year. Winter-buds obtuse, dark chestnut-brown, pubescent, nearly ⅛′ long. Bark of the trunk ¾′—1¼′ thick, red-brown, and deeply divided into broad flat connected ridges covered with thin closely appressed plate-like scales. Wood light, soft, not strong, brittle, coarse-grained, pale brown tinged with red, with thin nearly white sapwood.
Distribution. Rocky banks of streams usually at elevations between 2500° and 3000° on the Blue Ridge from southwestern Virginia to northern Georgia, generally singly or in small scattered groves of a few individuals.
Occasionally planted as an ornamental tree in the northern states, and in western Europe.
3. [Tsuga heterophylla] Sarg. Hemlock.
Leaves rounded at apex, conspicuously grooved, dark green and very lustrous on the upper surface, marked below by broad white bands of 7—9 rows of stomata, abruptly contracted at the base into slender petioles, ¼′—¾′ long and 1/16′—1/12′ wide, mostly persistent 4—7 years. Flowers: male yellow; female purple and puberulous, with broad bracts gradually narrowed to an obtuse point and shorter than their broadly ovate slightly scarious scales. Fruit oblong-ovoid, acute, sessile, ¾′—1′ long, with slightly puberulous oval scales, often abruptly narrowed near the middle, and dark purple puberulous bracts rounded and abruptly contracted at apex; seeds ⅛′ long, furnished with occasional oil-vesicles, one third to one half as long as their narrow wings.
A tree, frequently 200° high, with a tall trunk 6°—10° in diameter, and short slender usually pendulous branches forming a narrow pyramidal head, and slender pale yellow-brown branchlets ultimately becoming dark reddish brown, coated at first with long pale hairs, and pubescent or puberulous for five or six years. Winter-buds ovoid, bright chestnut-brown, about 1/16′ long. Bark on young trunks thin, dark orange-brown, and separated by shallow fissures into narrow flat plates broken into delicate scales, becoming on fully grown trees 1′—1½′ thick and deeply divided into broad flat connected ridges covered with closely appressed brown scales more or less tinged with cinnamon-red. Wood light, hard and tough, pale brown tinged with yellow, with thin nearly white sapwood; stronger and more durable than the wood of the other American hemlocks; now largely manufactured into lumber used principally in the construction of buildings. The bark is used in large quantities in tanning leather; from the inner bark the Indians of Alaska obtain one of their principal articles of vegetable food.
Distribution. Southeastern Alaska, southward near the coast to southern Mendocino County, California, extending eastward over the mountains of southern British Columbia, northern Washington, Idaho and Montana, to the western slopes of the continental divide, and through Oregon to the western slopes of the Cascade Mountains, sometimes ascending in the interior to elevations of 6000° above the sea; most abundant and of its largest size on the coast of Washington and Oregon; often forming a large part of the forests of the northwest coast.
Frequently planted as an ornamental tree in temperate Europe.
4. [Tsuga Mertensiana] Sarg. Mountain Hemlock. Black Hemlock.
Leaves standing out from all sides of the branch, remote on leading shoots and crowded on short lateral branchlets, rounded and occasionally obscurely grooved or on young plants sometimes conspicuously grooved on the upper surface, rounded and slightly ribbed on the lower surface, bluntly pointed, often more or less curved, stomatiferous above and below, with about 8 rows of stomata on each surface, light bluish green or on some individuals pale blue, ½′—1′ long, about 1/16′ wide, abruptly narrowed into nearly straight or slightly twisted petioles articulate on bases as long or rather longer than the petioles; irregularly deciduous during their third and fourth years. Flowers: male borne on slender pubescent drooping stems, violet-purple; female erect, with delicate lustrous dark purple or yellow-green bracts gradually narrowed above into slender often slightly reflexed tips and much longer than their scales. Fruit sessile, oblong-cylindric, narrowed toward the blunt apex and somewhat toward the base, erect until more than half grown, pendulous or rarely erect at maturity, ⅝′—3′ long, with thin delicate oblong-obovate scales gradually contracted from above the middle to the wedge-shaped base, rounded at the slightly thickened more or less erose margins, puberulous on the outer surface, usually bright bluish purple or occasionally pale yellow-green, four or five times as long as their short-pointed dark purple or brown bracts; seeds light brown, ⅛′ long, often marked on the surface next their scales with 1 or 2 large resin-vesicles, with wings nearly ½′ long, broadest above the middle, gradually narrowed below, slightly or not at all oblique at the rounded apex.
A tree, usually 70°—100° but occasionally 150° high, with a slightly tapering trunk 4°—5° in diameter, gracefully pendant slender branches furnished with drooping frond-like lateral branches, their ultimate divisions erect and forming an open pyramid surmounted by the long drooping leading shoot, and thin flexible or sometimes stout rigid branchlets light reddish brown and covered for two or three years with short pale dense pubescence, becoming grayish brown and very scaly. Winter-buds acute, about ⅛′ long, the scales of the outer ranks furnished on the back with conspicuous midribs produced into slender deciduous awl-like tips. Bark 1′—1½′ thick, deeply divided into connected rounded ridges broken into thin closely appressed dark cinnamon scales shaded with blue or purple. Wood light, soft, not strong, close-grained, pale brown or red, with thin nearly white sapwood; occasionally manufactured into lumber.
Distribution. Exposed ridges and slopes at high altitudes along the upper border of the forest from southeastern Alaska, southward over the mountain ranges of British Columbia to the Olympic Mountains of Washington, and eastward to the western slopes of the Selkirk Mountains in the interior of southern British Columbia, and along the Bitter Root Mountains to the headwaters of the Clearwater River, Idaho; along the Cascade Mountains of Washington and Oregon, on the mountain ranges of northern California, and along the high Sierra Nevada to the cañon of the south fork of King’s River, California; in Alaska occasionally descending to the sea-level, and toward the southern limits of its range often ascending to elevations of 10,000°.
Often planted as an ornamental tree in western and central Europe, and rarely in the eastern United States.