Plant 208

Pseudotsuga menziesii (Mirb.) Franco (Pinaceae)


Douglas fir

Described by the nineteenth-century Scottish botanist and plant collector David Douglas as 'one of the most striking and truly graceful objects in nature', the Douglas fir is the largest species in the pine family. Specimens currently growing in Britain have been measured as among the country's tallest trees.

The native range of Douglas fir is western North America but it has been successfully introduced to many other temperate regions. The species is divided into coastal (var. menziesii) and interior (var. glauca) varieties. Coastal Douglas fir occurs from central British Columbia down the Pacific Coast to southern California. Interior, or Rocky Mountain, Douglas fir is found at high elevations in the Pacific Coast Ranges from Alberta to Puebla in Central Mexico. Factors that limit the species' distribution include temperature in the north and moisture in the south. Southern populations of var. glauca are scattered and found only in areas with permanent moisture such as by north-facing canyon walls or at high altitudes where winter snowfall occurs.

Coastal Douglas fir commonly measure up to 75 m tall with the largest specimens reaching 100 m tall, such as the Doerner Fir in Oregon, the world's third tallest tree. The interior Douglas fir is slow growing and has a short lifespan but is hardier that then the coastal variety; it is identified by its eponymous blue-green foliage. Other distinctions include the bracts of mature cones which are appressed on the coastal variety and reflexed on the interior variety.

Its Greek-derived generic name means false hemlock in reference to its resemblance to the genus Tsuga. The specific epithet commemorates Archibald Menzies who first described the tree during a 1790 voyage to the northeast Pacific Ocean. The common name refers to David Douglas who collected seed along the Columbia River in 1824 and returned them to Britain, where the species was introduced in 1827. It is not a true fir; these belong to the genus Abies.

Douglas fir has long been used as timber providing material for furniture, beams, cladding and flooring. The fast-growing coastal variety produces timber of great length that is useful in construction and the stouter, slow-growing interior variety has timber which is dense and has been used as railroad trestles. Historically, in Hawaii the preferred material for war-canoe construction was salvaged from Douglas-fir driftwood. In the United States it is a popular Christmas trees because of its beautiful fragrance and attractive colour.

Further reading

Bean WJ 1976. Trees and shrubs hardy in the British Isles. Vol. 3. John Murray.

Farjon A 1990. Pinaceae: drawings and descriptions of the genera Abies, Cedrus, Pseudolarix, Keteleeria, Nothotsuga, Tsuga, Cathaya, Pseudotsuga, Larix and Picea. Koeltz Scientific Books.

Farjon A and Filer DF 2013. An atlas of the world's conifers: an analysis of their distribution, biogeography, diversity, and conservation status. Brill.

Neil Alderson