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''Pseudotsuga menziesii'' var. ''glauca'', or Rocky Mountain Douglas-fir, is an evergreen conifer native to the interior mountainous regions of western North America, from central British Columbia and southwest Alberta in Canada southward through the United States to the far north of Mexico.〔C. Michael Hogan (2008). ''Douglas-fir: "Pseudotsuga menzesii"'', GlobalTwitcher.com, ed. N. Stromberg ()〕 The range is continuous in the northern Rocky Mountains south to eastern Washington, eastern Oregon, Idaho, western and south-central Montana and western Wyoming, but becomes discontinuous further south, confined to "sky islands" on the higher mountains in Utah, Colorado, Arizona and New Mexico, with only very isolated small populations in eastern Nevada, westernmost Texas, and northern Mexico. It occurs from 600 m altitude in the north of the range, up to 3,000 m, rarely 3,200 m, in the south. Further west towards the Pacific coast, it is replaced by the related coast Douglas-fir (''Pseudotsuga menziesii'' var. ''menziesii''), and to the south, it is replaced by Mexican Douglas-fir in high mountains as far south as Oaxaca. Some botanists have grouped Mexican Douglas-fir with ''P. menziesii'' var. ''glauca'', but genetic and morphological evidence suggest that Mexican populations should be considered a different variety. Rocky Mountain Douglas-fir is most commonly treated as a variety (''Pseudotsuga menziesii'' var. ''glauca''),〔〔(【引用サイトリンク】url=http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=233500996 )〕 but has also been called a subspecies (''Pseudotsuga menziesii'' subsp. ''glauca'')〔Grimshaw, J., & Bayton, R. (2009). ''New Trees''. International Dendrology Society / Kew. ISBN 978-1-84246-173-0.〕 or more rarely (mainly in the past) a distinct species (''Pseudotsuga glauca'').〔Mayr, H. (1906). ''Fremdländische Wald- und Parkbäume für Europa'' (p.404 ). Berlin.〕 The strong ecological and genetic differentiation with intergradation limited primarily to postglacial contact zones in British Columbia supports infraspecific groupings. Some botanists have further split Rocky Mountain Douglas-fir into two varieties,〔Dallimore, W., & Jackson, A. B. (1966). ''A Handbook of Coniferae and Ginkgoaceae'', 4th ed. Arnold, London.〕 but these are not widely acknowledged and have only limited support from genetic testing.〔〔〔 ==Characteristics== Rocky Mountain Douglas-fir is a large tree, typically reaching 35–45 m in height and 1 m in diameter, with exceptional specimens known to 67 m tall, and 2 m diameter. It commonly lives more than 500 years and occasionally more than 1,200 years. The bark on young trees is thin, smooth, gray, and covered with resin blisters. On mature trees, it is moderately thick (3–6 cm), furrowed and corky though much less so than coast Douglas-fir. The shoots are brown to gray-brown, smooth, though not as smooth as fir shoots, and finely pubescent with scattered short hairs. The buds are a distinctive narrow conic shape, 3–6 mm long, with red-brown bud scales. The leaves are spirally arranged but slightly twisted at the base to be upswept above the shoot, needle-like, 2–3 cm long, gray-green to blue-green above with a single broad stomatal patch, and with two whitish stomatal bands below. The male (pollen) cones are 2–3 cm long, and are typically restricted to or more abundant on lower branches. Pollen cones develop over 1 year and wind-dispersed pollen is released for several weeks in the spring. The mature female seed cones are pendent, 4–7 cm long, 2 cm broad when closed, opening to 3–4 cm broad. They are produced in spring, purple (sometimes green) at first, maturing orange-brown in the autumn 5–7 months later. The seeds are 5–6 mm long and 3–4 mm broad, with a 12–15 mm wing. Both coast Douglas-fir and Rocky Mountain Douglas-fir produce abundant crops of seed approximately every 2–11 years. Seed is produced annually except for about 1 year in any 4-to-5-year period. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Pseudotsuga menziesii var. glauca」の詳細全文を読む スポンサード リンク
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