Pseudotsuga menziesii

Lore & Background

The Douglas-fir is an evergreen conifer in the pine family, though it is not a true fir, spruce, pine, or hemlock; its scientific name *Pseudotsuga* means "false hemlock." It is native to western North America and includes three varieties: coast, Rocky Mountain, and Mexican. The tree is medium-sized to extremely large, reaching 20–100 meters in height, with coast Douglas-firs approaching the upper limit. Trunks commonly reach 8 feet in diameter, with exceptional specimens nearly 5 meters across. The largest coast individuals regularly live over 500 years, with the oldest exceeding 1,300 years, while Rocky Mountain trees usually do not surpass 400 years. Historical records describe coast Douglas-firs over 120 meters tall, which would make them the tallest tree species on Earth. The leaves are flat, soft, linear needles 1.5–4 cm long, resembling fir needles but occurring singly and encircling the branches. In dense forests, lower branches are lost, with foliage starting as high as 110 feet off the ground; in brighter environments, branches remain lower. Young trees have thin, smooth, gray bark with resin blisters. On mature trees over 80 years old, the bark becomes very thick and corky, up to 14 inches thick, with deep vertical fissures and a layered, brown and lighter-colored texture. This bark provides exceptional fire resistance. Male cones are yellowish red, 5–12 mm long; female cones are green when young, maturing to reddish-brown or gray, 6–10 cm long, pendulous, with persistent scales and distinctive long, three-pointed bracts that protrude above each scale, resembling the back half of a mouse. Seeds are 5 mm long with a longer wing. The species was first documented by Archibald Menzies on Vancouver Island in 1791, and later reported by David Douglas. It is naturalized in Europe, Argentina, Chile, and New Zealand, where it is both a common lumber tree and, in New Zealand, considered an invasive wilding conifer subject to control.

Reader's Guide

Pseudotsuga menziesii is ecologically and economically significant as the dominant tree west of the Cascade Mountains in the Pacific Northwest. Its thick bark provides exceptional fire resistance, and its seeds are a crucial food source for small mammals such as moles, shrews, and chipmunks. Mature Douglas-fir forest is the primary habitat for the red tree vole and the spotted owl. The species is also naturalised in Europe, Argentina, Chile, and New Zealand, where it is both a common lumber tree and, in New Zealand, considered an invasive wilding conifer. The coast Douglas-fir variety grows larger and faster than the interior Rocky Mountain variety, and it competes well on most parent materials and slopes. The species exhibits considerable morphological plasticity, adapting to both moist coastal climates and drier interior sites. Its historical record includes fossils from the Miocene and Pliocene of Europe.

Did You Know?

• Despite its common name, Douglas-fir is not a true fir (genus Abies), spruce (Picea), pine (Pinus), or hemlock (Tsuga); its genus name Pseudotsuga means 'false hemlock'.
• The female cones have distinctive three-pointed bracts that are said to resemble the back half of a mouse, with two feet and a tail.