Pseudotsuga menziesii

Scientific name: Pseudotsuga menziesii (Mirb.) Franco 1950

Synonyms: Abies californica Steud., Abies douglasii (Sabine ex D.Don) Lindl., Abies drummondii Gordon, Abies menziesii Mirb., Abies mucronata Raf., Abies obliqua Bong. ex Gordon, Abies obliquata Raf. ex Gordon, Abies standishiana K.Koch, Abies taxifolia Poir., Abies taxifolia C.Presl, Abietia douglasii (Sabine ex D.Don) A.H.Kent, Picea douglasii (Sabine ex D.Don) Link, Pinus douglasii Sabine ex D.Don, Pinus taxifolia Lamb., Pseudotsuga douglasii (Sabine ex D.Don) Carrière, Pseudotsuga mucronata (Raf.) Sudw. ex Holz., Pseudotsuga taxifolia (Lindl.) Britton, Pseudotsuga vancouverensis Flous, Tsuga douglasii (Sabine ex D.Don) Carrière

Common names: Douglas fir, Douglas-fir, Douglas, Oregon pine, Douglastree

Description

Tree to 90(-100) m tall, with trunk to 3(-4.5) m in diameter. Bark reddish brown to grayish brown or even blackish, thick, breaking up with age into scaly, broad, interlacing ridges separated by deep furrows. Crown narrowly conical or narrowly egg-shaped to cylindrical with numerous short, slender, initially upwardly arched branches passing through horizontal to downswept with age. Twigs pale greenish yellow to reddish purple and minutely hairy, becoming gray and hairless with age, with inconspicuous, shallow grooves between the leaf bases. Buds 6-10 mm long, shiny reddish brown, not resinous. Needles sticking out to the sides and above, (1.5-)2-3(-4) cm long, 1-1.5 mm wide, pointed or rounded at the tip, yellowish green or dark green to bluish green or grayish green, the stomatal bands, pale whitish green. Pollen cones (10-)15-20 mm long, yellowish brown blushed with red. Seed cones 4-9(-10) cm long, 3-4 cm across, green before maturity, ripening yellowish brown to purplish brown, the seed scales flexible, the bracts pointed forward or sticking out. Seeds 5-7(-8) mm long, the wings 10-12(-14) mm long.

Western North America from central British Columbia south through the Coast and Cascade Ranges and Sierra Nevada to southern California and through the Rocky Mountains and other cordilleran ranges to northern Oaxaca (Mexico). Forming enormous pure stands (especially after fires) or mixed with various other conifers and a few hardwoods in lowland and montane forests on a wide variety of substrates; 0-3,000 m.

Conservation Status

Red List Category & Criteria: Least Concern

This species is a major component of the extensive coniferous forests of the Pacific Northwest of the USA and Canada. Logging has removed many large individuals but has not significantly reduced the population of mature trees. In the Rocky Mountains logging is significant in Canada, but less so farther south as the species becomes naturally more scattered. Past (and to an extent) present logging has had huge negative impacts on ‘old growth’ forests dominated by Douglas-fir. This is a threat to the ecosystem peculiar to old growth conifer forests, and its biodiversity, in the region. This variety is present in many protected areas, including some famous national parks.

References

Farjon, A. (2010). A Handbook of the World's Conifers. Koninklijke Brill, Leiden.
Eckenwalder, J.E. (2009) Conifers of the World: The Complete Reference. Timber Press, Portland.
IUCN Red List of Threatened Species, International Union for Conservation of Nature and Natural Resources. Cambridge, UK /Gland, Switzerland

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