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.
5. PSEUDOTSUGA Carr.
Pyramidal trees, with thick deeply furrowed bark, hard strong wood, with spirally marked wood-cells, slender usually horizontal irregularly whorled branches clothed with slender spreading lateral branches forming broad flat-topped masses of foliage, ovoid acute leaf-buds, the lateral buds in the axils of upper leaves, their inner scales accrescent and marking the branchlets with ring-like scars. Leaves petiolate, linear, flat, rounded and obtuse or acuminate at apex, straight or incurved, grooved on the upper side, marked on the lower side by numerous rows of stomata on each side of the prominent midrib, spreading nearly at right angles with the branch. Flowers solitary, the male axillary, scattered along the branches, oblong-cylindric, with numerous globose anthers, their connectives terminating in short spurs, the female terminal or in the axils of upper leaves, composed of spirally arranged ovate rounded scales much shorter than their acutely 2-lobed bracts, with midribs produced into elongated slender tips. Fruit an ovoid-oblong acute pendulous cone maturing in one season, with rounded concave rigid scales persistent on the axis of the cone after the escape of the seeds, and becoming dark red-brown, much shorter than the 2-lobed bracts with midribs ending in rigid woody linear awns, those at the base of the cone without scales and becoming linear-lanceolate by the gradual suppression of their lobes. Seeds nearly triangular, full, rounded and dark-colored on the upper side and pale on the lower side, shorter than their oblong wings infolding the upper side of the seeds in a dark covering; outer seed-coat thick and crustaceous, the inner thin and membranaceous; cotyledons 6—12, much shorter than the inferior radicle.
Pseudotsuga is confined to western North America, southern Japan, southwestern China and Formosa. Four species are recognized.