| Douglas-fir Pseudotsuga |
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|---|---|
| Pseudotsuga menziesii var. menziesii in Anacortes Community Forest Lands, Washington | |
| Scientific classification | |
| Kingdom: | Plantae |
| Division: | Pinophyta |
| Class: | Pinopsida |
| Order: | Pinales |
| Family: | Pinaceae |
| Genus: | Pseudotsuga Carrière |
| Species | |
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Douglas-fir is one of the English common names for evergreen coniferous trees of the genus Pseudotsuga ( /ˌsjuːdoʊˈtsuːɡə/)[1] in the family Pinaceae. Other common names include Douglas tree, and Oregon pine. There are five species, two in western North America, one in Mexico, and two in eastern Asia. Nineteenth-century botanists had problems in classifying Douglas-firs, due to the species' similarity to various other conifers better known at the time; they have at times been classified in Pinus, Picea, Abies, Tsuga, and even Sequoia. Because of their distinctive cones, Douglas-firs were finally placed in the new genus Pseudotsuga (meaning "false hemlock") by the French botanist Carrière in 1867. The genus name has also been hyphenated as Pseudo-tsuga.
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The common name Douglas-fir honours David Douglas, the Scottish botanist who first introduced P. menziesii into cultivation at Scone Palace in 1827.[2] Douglas is known for introducing many North American native conifers to Europe. The hyphen in the name indicates that Douglas-firs are not true firs, not being members of the genus Abies.[3]
Douglas-firs are medium-size to extremely large evergreen trees, 20–120 metres (70–390 ft) tall (although only Coast Douglas-firs reach such great height).[4] The leaves are flat, soft, linear, and completely encircle the branches (this can be useful in distinguishing it from other species), generally resembling those of the firs. The female cones are pendulous, with persistent scales (unlike true firs), and are distinctive in having a long tridentine (three-pointed) bract that protrudes prominently above each scale.
Uniquely among conifers, the Douglas-fir has cones with 3-lobed bracts sticking out between the scales. The cones hang down rather than sticking up as in true firs. The needles are 2–4 centimetres (0.8–1.6 in) long and occur singly rather than in fascicles.
Coast Douglas-fir has attained heights of 393 feet (120 m). That was the estimated height of the tallest conifer ever well-documented, the Mineral Tree (Mineral, Washington), measured in 1924 by Dr. Richard E. McArdle,[5] former chief of the U.S. Forest Service.[6] The volume of that tree was 515 cubic metres (18,190 cu ft). The tallest living individual is the Brummitt (Doerner) Fir in Coos County, Oregon, 99.4 metres (326 ft) tall.[7] Only Coast Redwood[8] reach greater heights based on current knowledge of living trees. At Quinault, Washington, is found a collection of the largest Douglas-firs in one area. Quinault Rain Forest hosts the most of the top ten known largest Douglas-firs.
As of 2009[update], the largest Douglas-firs in the world are, by volume:[9]
By far the best-known is the very widespread and abundant North American species Pseudotsuga menziesii, a taxonomically complex species[10] divided into two major varieties (treated as distinct species or subspecies by some botanists): coast Douglas-fir or "green Douglas-fir", on the Pacific coast; and Rocky Mountain Douglas-fir or "interior Douglas-fir", in the interior west of the continent extending as far inland as Calgary, Alberta.[11] Some botanists divide the latter in turn into two varieties, "blue Douglas-fir" or "Colorado Douglas-fir" (var. glauca) in the southern Rocky Mountains, and "gray Douglas-fir" or "Fraser River Douglas-fir" (var. caesia) in the northern Rocky Mountains.
All of the other species are of restricted range and little-known outside of their respective native environments, and even there are often rare and only of very scattered occurrence in mixed forests; all those are listed as being of unfavourable conservation status.
Douglas-fir wood is used for structural applications that are required to withstand high loads. It is used extensively in the construction industry. Other examples include its use for homebuilt aircraft such as the RJ.03 IBIS canard. Very often, these aircraft were designed to utilize Sitka spruce, which is becoming increasingly difficult to source in aviation quality grades. Oregon pine is also used in boat building when it is available in long fairly knot-free lengths. Most timber now comes from plantation forests in North America which are managed to produce faster growing timber with fewer knots. This timber is generally lighter but weaker. Traditionally, Oregon pine was used in mast building due to its ablilty to resist bending loads without fracturing. This was based on using older native forest wood with a high number of growth rings per inch. This sort of wood is seldom available new but can be sourced fron merchants dealing in recycled timber. Native Oregon pine is considerably heavier than Sitka spruce, which is about the same weight as Western red cedar, but with far better bending characteristics than cedar. Large-sized Oregon pine, as used in beams, is inclined to split as it dries, like oak, but this does not reduce its strength.
Douglas-fir is one of the most commonly marketed Christmas tree species in the United States, where they are sold alongside firs like Noble Fir and Grand Fir. Douglas-fir Christmas trees are usually trimmed to a near perfect cone instead of left to grow naturally like Noble and Grand firs.[14]
Douglas-firs are used as food plants by the larvae of some Lepidoptera species, including Autumnal Moth, Bordered White, The Engrailed, Pine Beauty and Turnip Moth. The gelechiids Chionodes abella and Chionodes periculella and the tortrix moth Cydia illutana have been specifically recorded on P. menziesii.
A California Native American myth explains that each three-ended bract is the tail and two tiny legs of a mouse that hid inside the scales of the tree's cones during forest fires, and the tree was kind enough to be its enduring sanctuary.
A Douglas-fir species, Pseudotsuga menziesii, is the state tree of Oregon.
In the American television series Twin Peaks, primary character Special Agent Dale Cooper displays a fascination with the firs upon arriving in the titular town.
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