Douglas-fir

Douglas-fir

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Douglas-fir

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 genus name has also been hyphenated as Pseudo-tsuga.

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
Uses
Diseases
Trivia
References
External links

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 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^[3]. 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. 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 . 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 ^[4] and Australian Mountain Ash (Eucalyptus regnans) ^[5] reach greater heights based on current knowledge of living trees.

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)^[6], 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

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 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. Douglas-fir is the most commonly marketed Christmas tree species in the United States, where they are sold along with 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.^[7]

This tree supports a variety of wildlife both with its shelter and seeds. This tree has also been adopted for horticultural use.

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.^[8]

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 north 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.^[9]

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.^[10]^[11]