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Pseudotsuga

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Douglas-fir
Pseudotsuga menziesii subsp. menziesii in Anacortes Community Forest Lands, Washington
Scientific classification
Kingdom:
Plantae
Division:
Pinophyta
Class:
Pinopsida
Order:
Pinales
Family:
Pinaceae
Genus:
Pseudotsuga

Species

See text

Douglas-fir is the common name applied to coniferous trees of the genus Pseudotsuga in the family Pinaceae. There are five species, two in western North America, one in Mexico and two in eastern Asia. The Douglas-firs gave 19th century botanists problems due to their 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 the distinctive cones, Douglas-firs were finally placed in the new genus Pseudotsuga (meaning "false Tsuga") by the French botanist Carrière in 1867.

The common name honours David Douglas, the Scottish botanist who first introduced the tree into cultivation in 1826. Douglas is known for introducing many North American native conifers to Europe. The hyphen in the common name indicates that Douglas-firs are not true firs; i.e. they are not members of the genus Abies.[1]

The Douglas-firs are medium-size to large or very large evergreen trees, to 20-120 m tall. The leaves are flat and needle-like, generally resembling those of the firs. The female cones are pendulous, with persistent scales (unlike true firs), and are distinct in having a long tridentine (three-pointed) bract that protrudes prominently above each scale.

Douglas-firs are used as food plants by the larvae of some Lepidoptera species including Autumnal Moth, Bordered White, The Engrailed, Pine Beauty, Turnip Moth and the gelechiids Chionodes abella and Chionodes periculella which have both been recorded on P. menziesii.

A Californian Native American myth explains that each of the three-ended bracts are a tail and two tiny legs of the mice who hid inside the scales of the tree's cones, which was kind enough to be the enduring sanctuary for them during forest fires.

Species and varieties

Coast Douglas-fir cone, from a tree grown from seed collected by David Douglas

By far the best-known is the very widespread and abundant North American species Pseudotsuga menziesii, a taxonomically complex species[2] divided into two major subspecies (treated as distinct species 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[3]. The latter is in turn divided 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. The species as a whole is generally known as simply "Douglas-fir", or as "Common Douglas-fir"; other less widely used names include "Oregon Douglas-fir", "Douglas Tree", and "Oregon Pine". It is the state tree of Oregon.

Coast Douglas-fir can attain heights of 120 metres (394 ft). That was the height of the tallest tree (of any species) ever well-documented, the Mineral Tree (Mineral, Washington), measured several times between 1911 and 1925 by Richard McCardle, a University of Washington forester. The volume of that tree was 515 cubic metres (18,190 cu ft). The tallest extant individual is the Brummitt Fir (Coos Bay, Oregon) some 103.3 metres (339 ft) at greatest length of stem. Only Coast Redwood grow taller.[4]

The specific name, menziesii, is after Archibald Menzies, a Scottish physician and rival naturalist to David Douglas, who first documented the tree on Vancouver Island in 1791. Away from its native area, it is also extensively used in forestry as a plantation tree for timber in Europe, New Zealand, southern South America and elsewhere. It is also naturalised throughout Europe (Austria with Liechtenstein, Belgium, Britain, Bulgaria, Czech Republic, Denmark, Finland, France, Germany, Ireland, Switzerland, Italy, Yugoslavia, Portugal, Poland, Romania, and Sweden)[5], Chile (called commonly Pino Oregón) and New Zealand, sometimes to the extent of becoming an invasive species subject to control measures.

Coast Douglas-fir branch
Rocky Mountain Douglas-fir twig
The buds of a Coast Douglas-fir

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, occurring in mixed forests; all are listed as being of unfavourable conservation status.

North America
Asia

Uses

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. Very often, these aircraft were designed to utilize Sitka Spruce, which is becoming increasingly difficult to source in aviation quality grades. Douglas-fir are also the most common Christmas trees in the United States where they are sold alongside true firs like Noble and Grand. Douglas-fir Christmas trees are usually trimmed to a near perfect cone instead of left to grow naturally like Noble and Grand.[6]

Diseases

Main article: List of douglas-fir diseases

Trivia

  • A tree cut down in 1902 at Lynn Valley on the northern shore of the city of Vancouver, British Columbia was reported to have measured 415 feet (approximately 126 metre) in height, and over 14 feet (4.3 metre) in diameter.[7]

References

  1. ^ Little, E. L. (1953). Check List of native and naturalized trees of the United States (including Alaska). Washington D.C.: U.S. Department of Agriculture. USDA Agricultural Handbook 41.
  2. ^ Li, Peng (1989). "Rangewide patterns of allozyme variation in Douglas-fir". Canad. J. Forest Res. 19: 149–161. doi:10.1139/x89-022. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help); Unknown parameter |quotes= ignored (help)
  3. ^ Edworthy Park - Calgary, Alberta - Wikipedia Entries on Waymarking.com
  4. ^ Van Pelt, Robert (2001). Forest Giants of the Pacific Coast. University of Washington Press. pp. Introduction XVI. ISBN 0295981407.
  5. ^ http://193.62.154.38/cgi-bin/nph-readbtree.pl/feout?FAMILY_XREF=&GENUS_XREF=Pseudotsuga&SPECIES_XREF=menziesii&TAXON_NAME_XREF=&RANK= Distribution of Douglas-fir
  6. ^ National Christmas Tree Assoc http://www.christmastree.org/trees/douglas.cfm
  • [7] British Columbia Forest History Newsletter, Jan. 1996 [1]
  • [3] The Trees That Made Britain, BBC Wales.
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