Syn: Abies menziesii Mirbel 1825; A. mucronata Rafinesque; A. taxifolia Poiret 1805, not Desfontaines 1804; Pinus taxifolia Lambert 1803, not Salisbury 1796; Pseudotsuga douglasii (Lindley) Carrière; Ps. mucronata (Rafinesque) Sudworth; Ps. taxifolia (Lambert) Britton (Lipscomb 1993). In fact, an extremely complex nomenclatural controversy surrounded this species from 1800 to 1950, during which time it went through many names that, for one reason or another, were shown to be illegitimate; for a detailed recounting of this controversy, see Reveal [n.d.].
Flous (1934a, 1934b) named an excessively large number of taxa throughout the American range of the genus Pseudotsuga based on cone characters that proved poorly formulated, unreliable and subject to individual variation. Little (1952) subsequently provided a categorical rejection of Flous' interpretation. Snajberk and Zavarin (1976) then performed a rangewide analysis of needle terpene compositions that found consistent differences between coastal, Sierra Nevada, northern interior, and southern interior regions. Peng and Adams (1989) presented very limited preliminary evidence from Mexico suggesting that (at least some) Douglas-fir in NE Mexico is genetically very distinct from the taxon in North America. The most recent work, by Adams and colleagues (Adams et al. 2012, Adams and Stoehr 2013, Adams et al. 2013) has again examined terpenes, along with leaf essential oils and genetic markers. This work confirmed the status of Ps. macrocarpa as a clearly distinct taxon, and provided new detail on differentiation within Ps. menziesii. The terpene data strongly support the traditional division into coastal and interior subspecies, with no significant discontinuities over the long latitudinal range of the species; while the genetic data offer some weak support for the existence of a distinct Oaxacan variety.
Trees with a single round trunk to 100 m tall and 440 cm dbh, with a narrow to broadly conic crown that typically becomes flattened or irregular in age; most trees more than about 350 years old have primarily epicormic branches (Van Pelt and Sillett 2008). Bark variable; gray to black or red-brown, generally with longitudinal fissures, scaly, sometimes flaking. Twigs slender, yellowish-green and minutely pubscent, turning gray and glabrous, bearing small circular leaf scars. Leaf buds ovoid, acute, 10 × 5 mm, not resinous. Leaves radially inserted but sometimes appearing 2-ranked on shade foliage; 15-30(-40) × 1.2-1.5 mm, various shades of green (yellow-green to dark-, gray-, or blue-green, usually uniform color on a branch, but adjacent branches on the same tree can have markedly different color), apex obtuse to acute. Pollen cones 15-20 mm long, yellow-red. Seed cones hanging on 5-10 mm long peduncles, ovoid, variably elongate, obtuse or pointed, 4-10 × 3-3.5 cm when opened, green with yellow-green 3-pointed bracts, ripening to gray or golden brown with lighter, straight to reflexed bracts. Seeds 6-8 × 4-5 mm, light brown, with a 9-14 mm long, yellow-brown wing (Lipscomb 1993, Farjon 2010). Detailed information on pollen, including photomicrography, is provided by Davis (1999).
Canada: British Columbia and Alberta; United States: Washington, Oregon, California, Idaho, Montana, Wyoming, Nevada, Utah, Colorado, Arizona, New Mexico, and Texas; Mexico: Chihuahua, Coahuila, Durango, Hidalgo, Nuevo León, Oaxaca, Sonora, and Zacatecas. The coastal subspecies menziesii occurs from central British Columbia south along the Pacific Coast for about 2,200 km to latitude 34° 44'. The interior subspecies glauca is found in the intermountain west, and along the Rocky Mountains and both Sierra Madre chains from Alberta to Oaxaca. Both subspecies tend to occur at progressively higher elevations from north to south. The principal limiting factors are temperature in the north of the range and moisture in the south. Consequently, Douglas-fir is found mainly on southerly slopes in the northern part of its range, and on northerly exposures in the southern part. At high elevations in the southern Rocky Mountains, however, Douglas-fir grows on the sunny slopes and dry rock exposures (Burns and Honkala 1990). See also Thompson et al. (1999).
See var. menziesii. This is the largest member of the Pinaceae (the second largest, Picea sitchensis, grows with P. menziesii in the coastal forests of NW North America) and larger by far than the other species in the genus.
See var. menziesii.
Many chronologies representing both varieties exist. The species has been used extensively in climate reconstruction and archeological dating. It has also been employed in ecological studies and stable isotope work.
Pseudotsuga menziesii is one of the world's most important timber trees, valued in both the Old and New worlds (Burns and Honkala 1990, Lipscomb 1993). It has been widely planted in New Zealand and is there regarded as an invasive weed.
Douglas-fir was first described by Archibald Menzies (1754-1842), who discovered it on Vancouver Island during the 1790 voyage by Captain Vancouver to the northeast Pacific Ocean. The species' epithet honors Menzies. The name Douglas-fir commemorates David Douglas, who collected the species along the lower Columbia River in 1824; the seeds that he sent back to England were eagerly received and quickly established the tree as a garden favorite and an important agroforestry species.
"Douglas-fir ... has been a major component of the forests of western North America since the mid-Pleistocene (Hermann 1985). Although the fossil record indicates that the native range of Douglas-fir has never extended beyond western North America, the species has been successfully introduced in the last 100 years into many regions of the temperate forest zone (Hermann 1987)" (Lipscomb 1993).
Douglas-fir is the state tree of Oregon (Lipscomb 1993).
Both varieties are host to the dwarf mistletoe Arceuthobium douglasii (Hawksworth and Wiens 1996).
This is one of the most-studied conifers in the world.
Adams, Robert P., J. Jesús Vargas-Hernández, M. Socorro González Elizondo, G. Hunter, T. A. Fairhall, David Thornburg, and Frank Callahan. 2012. Geographic variation in leaf essential oils of Douglas fir (Pseudotsuga menziesii). Phytologia 94(2).
Adams, Robert P., and M. Stoehr. 2013. Multivariate detection of hybridization using conifer terpenes II: Analyses of terpene inheritance patterns in Pseudotsuga menziesii F1 hybrids. Phytologia 95: 42–57.
Adams, R. P., J. Jesús Vargas-Hernández, M. Socorro González Elizondo, G. Hunter, T. A. Fairhall, David Thornburg, and Frank Callahan. 2013. Taxonomy of Douglas fir (Pseudotsuga menziesii) infraspecific taxa: vars. menziesii, glauca and oaxacana: nrDNA, cpDNA sequences and leaf essential oils. Phytologia 95(1).
Davis, Owen K. 1999. Pollen Grain Morphology Larch. URL=http://geo.arizona.edu/palynology/pid00013.html, accessed 2001.12.11.
Flous, F. 1934a. Deux espèces nouvelles de Pseudotsuga Américains. Bull. Soc. Hist. Nat. Toulouse 66: 211-224.
Flous, F. 1934b. Diagnoses d'espèces et variétés nouvelles de Pseudotsuga Américains. Bull. Soc. Hist. Nat. Toulouse 66: 329-346.
Little, E.L., Jr. 1952. The genus Pseudotsuga (Douglas-fir) in North America. Leaflets Western Botany 6: 181-198.
Peng Li and W.T. Adams. 1989. Rangewide patterns of allozyme variation in Douglas-fir. Canadian Journal of Forest Research 19: 149-161.
Reveal, James R. [no date]. A Nomenclatural Morass. http://www.plantsystematics.org/reveal/pbio/LnC/dougfir.html, accessed 2011.05.20.
Snajberk, K. and E. Zavarin. 1976. Mono- and sesqui-terpenoid differentiation of Pseudotsuga of the United States and Canada. Biochem. Syst. Ecol. 4:159-163.
Van Pelt, R., and Sillett, S. C. 2008. Crown development of coastal Pseudotsuga menziesii, including a conceptual model for tall conifers. Ecological Monographs 78(2):283–311.
Last Modified 2015-01-24