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 Carričre 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

Coast Douglas-fir can attain heights of . 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 . The tallest extant individual is the Brummitt Fir (Coos Bay, Oregon) some tall, and 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

North America

• Coast Douglas-fir, Pseudotsuga menziesii var. menziesii
  • Rocky Mountain Douglas-fir, Pseudotsuga menziesii var. glauca
• Mexican Douglas-fir, Pseudotsuga lindleyana
• Bigcone Douglas-fir, Pseudotsuga macrocarpa

Asia

• Japanese Douglas-fir, Pseudotsuga japonica
• Chinese Douglas-fir, Pseudotsuga sinensis var. sinensis
  • Narrow-cone Chinese Douglas-fir, Pseudotsuga sinensis var. gaussenii
  • Short-leaf Chinese Douglas-fir, Pseudotsuga sinensis var. brevifolia
  • Yunnan Douglas-fir, Pseudotsuga sinensis var. forrestii
  • Taiwan Douglas-fir, Pseudotsuga sinensis var. wilsoniana

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]fagv fag

Diseases

Trivia

• The tallest tree in the United Kingdom is a Douglas-fir (Pseudotsuga menziesii). The tree, growing in Reelig Glen by Inverness is called Dughall Mor and stands at 64 m. It was measured in 2005 by Tony Kirkham and Jon Hammerton from the Royal Botanic Gardens, Kew, the late Jim Paterson from The Tree Register and David Jardine of The Forestry Commission.^[7]

• On May 14 2001, a Douglas-fir was planted in honor of Douglas Adams after his death on May 11 2001. They are also sometimes planted on Towel Day.

• 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 (126.5 m) in height, and 14 feet 3 in. (4.3 m) in diameter.^[8]

• New research suggests Douglas-fir could grow to a maximum height of between 430 feet (131 m) and 476 feet (145 m) at which point water supply would fail.^[9][10]

References

External links

• Arboretum de Villardebelle - cone photos Images of cones of selected species
• Gymnosperm Database
• Dughall Mor at Forestry Commission
• The Tree Register

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