Tsuga mertensiana
| Tsuga mertensiana | |
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| Mountain hemlock in Henry M. Jackson Wilderness, Washington |
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| Scientific classification | |
| Kingdom: | Plantae |
| Division: | Pinophyta |
| Class: | Pinopsida |
| Order: | Pinales |
| Family: | Pinaceae |
| Genus: | Tsuga |
| Species: | T. mertensiana |
| Binomial name | |
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Tsuga mertensiana (Bong.) Carr. |
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| Natural range of Tsuga mertensiana | |
Tsuga mertensiana, known as mountain hemlock, is a species of hemlock native to the west coast of North America, with its northwestern limit on the Kenai Peninsula, Alaska, and its southeastern limit in northern Tulare County, California.Mertensiana refers to Karl Heinrich Mertens (1796–1830), a German botanist who collected the first specimens as a member of a Russian expedition in 1826-1829.
Tsuga mertensiana is a large evergreen coniferous tree growing to 20 to 40 m (66 to 131 ft) tall, with exceptional specimens as tall as 59 m (194 ft) tall. They have a trunk diameter of up to 2 m (6 ft 7 in). The bark is thin and square-cracked or furrowed, and gray in color. The crown is a neat, slender, conic shape in young trees with a tilted or drooping lead shoot, becoming cylindric in older trees. At all ages, it is distinguished by the slightly pendulous branchlet tips. The shoots are orange–brown, with dense pubescence about 1 mm (1⁄16 in) long. The leaves are needle-like, 7 to 25 mm (1⁄4 to 1 in) long and 1 to 1.5 mm (1⁄32 to 1⁄16 in) broad, soft, blunt-tipped, only slightly flattened in cross-section, pale glaucous blue-green above, and with two broad bands of bluish-white stomata below with only a narrow green midrib between the bands; they differ from those of any other species of hemlock in also having stomata on the upper surface, and are arranged spirally all around the shoot.
The cones are small (but much longer than those of any other species of hemlock), pendulous, cylindrical, 30 to 80 mm (1 to 3 in) long and 8 to 10 mm (5⁄16 to 3⁄8 in) broad when closed, opening to 12 to 35 mm (1⁄2 to 1 3⁄8 in) broad, superficially somewhat like a small spruce cone. They have thin, flexible scales 8 to 18 mm (5⁄16 to 11⁄16 in) long. The immature cones are dark purple (rarely green), maturing red–brown 5 to 7 months after pollination. The seeds are red–brown, 2 to 3 mm (1⁄16 to 1⁄8 in) long, with a slender, 7 to 12 mm (1⁄4 to 1⁄2 in)-long pale pink–brown wing.
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