Douglas-fir

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Douglas-fir

Coast Douglas-fir

Scientific classification

Kingdom:	Plantae
Division:	Pinophyta
Class:	Pinopsida
Order:	Pinales
Family:	Pinaceae
Genus:	Pseudotsuga Carrière

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.

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

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 20-100 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.

1 Species and varieties
2 Uses
3 Diseases
4 References
5 External links

[edit] Species and varieties

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. 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 can attain heights of 100 m (330 feet), second only to the Coast Redwood (old claims of trees up to 126 m (415 feet) have never been verified), and is the state tree of Oregon. The specific name, menziesii, is after Archibald Menzies, a Scottish physician and rival naturalist to David Douglas, who first discovered 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 in the British Isles, Chile 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 subsp. menziesii
- Rocky Mountain Douglas-fir, Pseudotsuga menziesii subsp. 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

[edit] Uses

Douglas-fir wood is used for structural applications that require 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 utilise Sitka Spruce, which is getting increasingly difficult to source in aviation quality grades.

[edit] Diseases

Main article: List of douglas-fir diseases

[edit] References

^ 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.
^ Li, Peng; W. T. Adams (1989). Rangewide patterns of allozyme variation in Douglas-fir. Canad. J. Forest Res. 19: 149-161.