Pseudotsuga menziesii

(Mirbel) Franco 1950

Common names

Douglas-fir; Douglas, yellow or red spruce; Oregon pine, Douglastree (Peattie 1950), sapin de Douglas (French) (Lipscomb 1993); red-fir, piño Oregon (Spanish) (Burns & Honkala 1990).

Taxonomic notes

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; P. mucronata (Rafinesque) Sudworth; P. taxifolia (Lambert) Britton (Lipscomb 1993).

There are two intergrading varieties, menziesii and glauca, sympatric in southern BC and northeastern WA (Lipscomb 1993).

Douglas-fir was first described by Archibald Menzies (1754-1842), who discovered it on Vancouver Island during the 1890 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 near 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.

Description

"Trees to 90(100) m; trunk to 4.4 m diam.; crown narrow to broadly conic, flattened in age. Twigs slender, pubescent, becoming glabrous with age. Leaves 15-30(-40) × 1-1.5mm, yellow-green to dark or bluish green, apex obtuse to acute. Pollen cones yellow-red. Seed cones 4-10 × 3-3.5 cm. Seeds 5-6 mm, wing longer than seed body" (Lipscomb 1993). Detailed information on pollen, including photomicrography, is provided by Davis (1999).

Range

W US & Can. The coastal variety menziesii occurs from central British Columbia south along the Pacific Coast for about 2,200 km (1,367 mi.) to latitude 34° 44'. The interior variety glauca is found along the Rocky Mountains to southern Arizona and New Mexico, where it merges imperceptibly into the closely related species P. lindleyana of Mexico. "Altitudinal distribution of both varieties of Douglas-fir (menziesii and glauca) increases from north to south, reflecting the effect of climate on distribution of the species. 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 & Honkala 1990). See also Thompson et al. (1999).

Big tree

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.

Oldest

See var. menziesii.

Dendrochronology

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.

Ethnobotany

Pseudotsuga menziesii is one of the world's most important timber trees, valued in both the Old and New worlds (Burns & Honkala 1990, Lipscomb 1993). It has been widely planted in New Zealand and is there regarded as an invasive weed.

Observations

Easily seen in the western USA and Canada. See vars. menziesii and glauca for details.

Remarks

One of the most-studied conifers in the world.

"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 subspecies are host to the dwarf mistletoe Arceuthobium douglasii (Hawksworth and Wiens 1996).

Citations

Davis, Owen K. 1999. Pollen Grain Morphology Larch. URL=http://geo.arizona.edu/palynology/pid00013.html, accessed 11-Dec-2001.

See also:

Arno & Gyer 1973.

Farjon (1990) provides a detailed account, with illustrations.

Lanner 1983.

FEIS database.