[15] There are records of former coast Douglas-firs exceeding 120 m (390 ft)[16][17] in height, which if alive today would make it the tallest tree species on Earth.

The leaves are flat, soft, linear needles 1.5–4 centimetres (1⁄2–1+1⁄2 in) long,[18] generally resembling those of the firs, occurring singly rather than in fascicles; they completely encircle the branches, which can be useful in recognizing the species.

As the trees grow taller in denser forest, they lose their lower branches, such that the foliage may start as high as 34 m (110 ft) off the ground.

Some of the mature bark is brown, while other parts are lighter colored with a cork-like texture; these develop in multiple layers.

The female cones are green when young, maturing to reddish-brown or gray, 6–10 cm (2+1⁄4–4 in) long;[18] they are pendulous, with persistent scales, unlike those of true firs.

They have distinctive long, trifid (three-pointed) bracts which protrude prominently above each scale and are said to resemble the back half of a mouse, with two feet and a tail.

[18] The massive mega-genome of Douglas-fir was sequenced in 2017 by the large PineRefSeq consortium, revealing a specialized photosynthetic apparatus in the light-harvesting complex of genes.

[23] The common name honors David Douglas, a Scottish botanist and collector who first reported the extraordinary nature and potential of the species.

[24][14] The specific epithet menziesii is after Archibald Menzies, a Scottish physician and rival naturalist to David Douglas.

Colloquially, the species is also known simply as Doug fir[8] or Douglas pine[8] (although the latter common name may also refer to Pinus douglasiana).

menziesii, the coast Douglas-fir, grows in the coastal regions from west-central British Columbia southward to Central California.

Fossils (wood, pollen) of Pseudotsuga are recorded from the Miocene and Pliocene of Europe (Siebengebirge, Gleiwitz, Austria).

glauca exhibits even greater plasticity, occurring in stands of interior temperate rainforest in British Columbia, as well as at the edge of semi-arid sagebrush steppe throughout much of its range, where it generates even deeper taproots still.

Adapted to a more moist, mild climate than the interior subspecies, it grows larger and faster than Rocky Mountain Douglas-fir.

[13] Mature or "old-growth" Douglas-fir forest is the primary habitat of the red tree vole (Arborimus longicaudus) and the spotted owl (Strix occidentalis).

The red vole nests almost exclusively in the foliage of the trees, typically 2–50 metres (5–165 ft) above the ground, and its diet consists chiefly of Douglas-fir needles.

[40] Native Hawaiians built waʻa kaulua (double-hulled canoes) from coast Douglas-fir logs that had drifted ashore.

[14] In addition early settlers used Douglas-fir for all forms of building construction, including floors, beams, and fine carving.

[44] Douglas-fir sees wide use in heavy timber structures, as its wood is strong, available in a number of specifications including kiln dried and grade stamped, and can be supplied in very long lengths to 60 feet.

West coast mills are sophisticated in their processing of timbers, making lead times predictable and availability reliable.