Douglas Fir

(Pseudotsuga menziesii)

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Douglas Fir (Pseudotsuga menziesii)

Identifying Characters: Douglas Fir is characterized by the prominent, three-pronged cone brachts. The needles are petiolate and leave a small, raised scar on the twig.

Similar Species: Bigcone Douglas Fir is limited in Southern California and is not found within the range of Douglas Fir. The cones of Bigcone Douglas Fir are much larger (4 to 6 inches in length) than those of Douglas Fir (2 to3.5 inches). Other conifers with conspicuous cone brachts are some firs (Abies) and western larches (Larix). The cones of firs stand upright on the branches, not handing below the branch as in Douglas Fir. The needles of western larches are whorled around a small stalk, not single and arranged in two irregular rows.

Measurements: Douglas Firs are often large trees reaching between 80 to 200 feet with occasional individuals exceeding 300 feet; diameter at breast height of mature individuals 2 to 5 feet.

Cones: Cones elongate-ovoid, hanging (pendant), light brown and borne on a short stalk; cones 2 to 3.5 inches in length; cone scales broad and rounded; cone brachts very large, protruding well beyond the ends of the cone scales, the apices three-pronged with the center prong long and narrow.

Needles: Needles spreading, in two very irregular rows, 0.75 to 1.25 inches in length; needles flattened, petiolate, and rounded at the tip, flexible; color variable by range, yellow-green along the pacific coast, and blue-green in the Rocky Mountains.

Bark: Bark very thick, red-brown to gray-brown, deeply furrowed into wide ridges.

Native Range: The latitudinal range of Douglas Fir is the greatest of any commercial conifer of western North America. Its native range, extending from latitude 19° to 55° N., resembles an inverted V with uneven sides. From the apex in central British Columbia, the shorter arm extends south along the Pacific Coast Ranges for about 2200 km (1,367 mi) to latitude 34° 44' N., representing the range of the typical coastal or green variety, menziesii; the longer arm stretches along the Rocky Mountains into the mountains of central Mexico over a distance of nearly 4500 km (2,796 mi), comprising the range of the other recognized variety, glauca- Rocky Mountain or blue. Nearly pure stands of Douglas Fir continue south from their northern limit on Vancouver Island through western Washington, Oregon, and the Klamath and Coast Ranges of northern California as far as the Santa Cruz Mountains. In the Sierra Nevada, Douglas-fir is a common part of the mixed conifer forest as far south as the Yosemite region. The range of Douglas-fir is fairly continuous through northern Idaho, western Montana, and northwestern Wyoming. Several outliers are present in Alberta and the eastern-central parts of Montana and Wyoming, the largest being in the Bighorn Mountains of Wyoming. In northeastern Oregon, and from southern Idaho south through the mountains of Utah, Nevada, Colorado, New Mexico, Arizona, extreme western Texas, and northern Mexico, the distribution becomes discontinuous. (Silvics of North America. 1990. Agriculture Handbook 654.)

Habitat: The Pacific Coast populations of Douglas Fir occur on moist but well-drained soils, often in pure, very large stands. The Rocky Mountain populations of the species are found primarily on rocky soils on mountain slopes in both pure stands and mixed with other species of conifers.