Douglas-fir Pseudotsuga
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
See text

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. The number of species has long been debated, but two in western North America and two to four in eastern Asia are commonly acknowledged.^[2][3] 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.

Name[link]

The common name Douglas-fir honors David Douglas, the Scottish botanist who first introduced P. menziesii into cultivation at Scone Palace in 1827.^[4] 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.^[5] Most dictionaries don't recognize this distinction, however, including Merriam-Webster and Webster's New World College Dictionary.

Description[link]

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).^[6] The leaves are flat, soft, linear, 2–4 centimetres (0.8–1.6 in) long, generally resembling those of the firs, occurring singly rather than in fascicles; they completely encircle the branches, which can be useful in recognizing the species. 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 (it resembles the back half of a mouse, with two feet and a tail).

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

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,^[7] former chief of the U.S. Forest Service.^[8] 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.^[9] Only Coast Redwood^[10] 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 known Douglas-firs in the world are, by volume:^[11]

1. Red Creek Tree (Red Creek, SW British Columbia) 12,320 cubic feet (349 m³)
2. Queets Fir (Queets River Valley-Olympic National Park) 11,710 cubic feet (332 m³)
3. Tichipawa (Quinalt Lake Rain Forest-Olympic National Park) 10,870 cubic feet (308 m³)
4. Rex (Quinalt Lake Rain Forest-Olympic National Park) 10,200 cubic feet (290 m³)
5. Ol' Jed (Jedediah Smith Redwoods State Park) 10,040 cubic feet (284 m³)

Species and varieties[link]

Coast Douglas-fir branch

Rocky Mountain Douglas-fir twig

By far the best-known is the very widespread and abundant North American species Pseudotsuga menziesii, a taxonomically complex species^[12] 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. According to some botanists, Rocky Mountain Douglas-fir extends south into Mexico to include all Mexican Douglas-fir populations,^[13] whereas others have proposed multiple separate species in Mexico^[14][15][16] and multiple varieties in the United States. Morphological and genetic evidence suggest that Mexican Douglas-fir should probably be considered a distinct variety within P. menziesii.^[17][18][19]

All of the other species are of restricted range and little-known outside of their respective native environments, where they are often rare and of scattered occurrence in mixed forests; all those have unfavorable conservation status. The taxonomy of the Asian Douglas-firs continues to be disputed,^[20] but the most recent taxonomic treatment accepts four species: three Chinese and one Japanese.^[2][3] The three Chinese species have been variously considered varieties of P. sinensis^[21] or broken down into additional species and varieties.^[22] In the current treatment, the Chinese species P. sinensis is further subdivided into two varieties: var. sinensis and var. wilsoniana.

North America[link]

• Pseudotsuga macrocarpa (Vasey) Mayr – Bigcone Douglas-fir
• Pseudotsuga menziesii (Mirb.) Franco
  • Pseudotsuga menziesii var. glauca (Beissn.) Franco – Rocky Mountain Douglas-fir
  • Pseudotsuga menziesii var. menziesii – Coast Douglas-fir
  • Pseudotsuga lindleyana (Roezl) Carrière – Mexican Douglas-fir

Asia[link]

• Pseudotsuga brevifolia W.C.Cheng & L.K.Fu – Short-leaf Chinese Douglas-fir
• Pseudotsuga forrestii Craib – Yunnan Douglas-fir
• Pseudotsuga japonica (Shiras.) Beissn. – Japanese Douglas-fir
• Pseudotsuga sinensis Dode – Chinese Douglas-fir
  • Pseudotsuga sinensis var. sinensis
  • Pseudotsuga sinensis var. wilsoniana – Taiwan Douglas-fir

Formerly placed here[link]

• Keteleeria davidiana (Bertrand) Beissn. (as P. davidiana Bertrand)^[22]

Uses[link]

The buds of a Coast Douglas-fir

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 ability 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.^[23]

Pests and diseases[link]

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.

Culture[link]

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.

The Douglas fir is featured at the center of the flag of the Cascadian independence movement.

See also[link]

• Tree: A Life Story

References[link]

External links[link]

Wikimedia Commons has media related to: Pseudotsuga menziesii

• Gymnosperm Database - Pseudotsuga'
• USDA treatment for Pseudotsuga
• Arboretum de Villardebelle: Images of Pseudotsuga species cones

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Tony Kirkham (born 30 August 1957) is the head Arboretum at Royal Botanic Gardens, Kew, where he has worked since 1978.^[1]

Career[link]

Tony started his career as an apprentice at Tilhill Forestry Nursery in Frensham in 1974. In 1976 he attended Merrist Wood Agricultural College where he gained his NCH in Arboriculture and the RFS Certificate in Arb. He worked in Germany as a climber for Kusche und Frotscher based in Hamburg. In 1978 he started at Kew as a Diploma student for 3 years where he gained the Kew diploma at honours. In 1981 he was appointed manager of the North Arboretum from where he progressed to become Head of the Arboretum and Horticultural Services in 2001.

In 1985 he was a member of an expedition to Chile collecting seeds for the collections in the arboretum at Kew. Since the destruction of many of Kew's oldest trees in the Great Storm of 1987 he has spearheaded the restocking of the collection. In some instance using specimens collected on collecting trips to the far east. Countries visited include: China, Taiwan, South Korea, Japan, the Russian far east and Sakhalin Island.

Kirkham has an infectious enthusiasm for his subject and is best known for his appearances in the BBC series 'A Year at Kew' and 'The Trees That Made Britain'.^[2][3] He also lectures to students at Kew as well as other professional & interested groups and is an examiner for the RFS Professional diploma in Arboriculture. Tony sits on various professional committees, including The RHS woody plant committee and the bursary advisory committee. The IDS Science and education committee and the horticultural advisory board of QuarryHill Botanical Garden in California. He is a trustee of TROBI, the Tree Register Of the British Isles.

Family[link]

Robert Kirkham, Tony's son is following in his father's footsteps by taking part in The Royal Parks apprenticeship, started in 2011. He is currently based at Richmond Park.

Awards[link]

In 2009 he was awarded the Associate of Honour by the RHS for his services to horticulture. Only 100 persons hold this award in the British isles.

Kirkham sits on many professional committees including IDS, science and education committee, RHS, bursaries committee and the woody plant committee.

References[link]

External links[link]

• "A year at Kew" series page at Kew
• "Trees that made Britain" page at BBC
• [1] Royal Botanic Gardens Kew

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