Fir, common name for any of a genus of trees (see Pine). The trees, known as true firs, generally have a straight trunk with somewhat pyramidal growth. The branches grow in whorls from the trunk. The cones, which are erect at maturity, are composed of thin, close scales. Each scale bears two winged seeds. The flat leaves are scattered, with the midribs showing clearly on the whitish undersides.

About 25 species of true firs are widely scattered throughout the northern hemisphere. The silver fir of Europe sometimes reaches a height of 46 m (150 ft), with large boughs curved upward at their outer extremities. The leaves are dark green above, with two white lines beneath. When seen from below, the tree appears to have a silvery color. It is abundant in the mountains of southern and central Europe. It is also found in Asia, in the Caucasus Mountains.

Ten species of fir are native to North America, growing chiefly in the region west of the Rocky Mountains. They achieve maximum growth in the Sierra Nevada and Cascade mountain ranges. The balsam fir is found from Virginia to the island of Newfoundland and northwestward to the Yukon and Labrador. It grows from 12 to 18 m (40 to 60 ft) high, and its leaves are highly fragrant and resinous. The balsam fir, probably the best known of the true firs, is used for pulpwood and yields the oleoresin known as Canada balsam. The noble fir, found in California, Washington, and Oregon, grows to a height of 30 to 60 m (100 to 200 ft), with a trunk as large as 2.4 m (8 ft) in diameter. The alpine fir is smaller than the noble fir, growing commonly from 24 to 30 m (80 to 100 ft) high. It is found from New Mexico to Alaska in the Rocky Mountains. The lowland or grand fir, growing from Montana to the Pacific Coast, at times reaches a height of 91 m (300 ft). True firs do not have the resin ducts that typify true pines or spruce, although these trees all resemble one another in softness of wood.

Scientific classification: Firs make up the genus Abies, of the family Pinaceae. The silver fir of Europe is classified as Abies alba; the balsam fir as Abies balsamea; the noble fir as Abies procera; the subalpine fir as Abies lasiocarpa, and the lowland, or grand, fir as Abies grandis.

See also Douglas Fir.