Firs Of North America, Economic Uses Of Firs
The true firs are about 40 species of conifer trees in the genus Abies, occurring in cool-temperate, boreal, and montane forests of the northern hemisphere. Firs are members of the pine family (Pinaceae).
Firs are characterized by flattened needles, usually having two white lines running the length of the leaf. Firs do not have a petiole joining the needles to the twigs, and after the foliage is shed large scars are left on the twigs. The cones of firs are held upright, and they shed their scales soon after the winged seeds have been dispersed, leaving a spike-like axis on the twig. Fir trees generally have a dense, spire-like crown. The bark of most species is rather smooth on younger trees, becoming somewhat scaly on older trees. Many species develop resin-containing blisters on the surface of their bark. Firs are not a prime species for sawing into lumber, but they are excellent as a source of pulpwood for the manufacturing of paper, and are also cultivated as Christmas trees and as ornamentals.
Douglas firs (Pseudotsuga spp.) are a closely related group of six species that occur in western North America and eastern Asia. Douglas firs are distinguished from true firs by their small, raised leaf scar, a petiole joining the leaf to the twig, and the distinctive, three-pointed bracts (scale-like leaves) that occur immediately below and close to the scales of their oval-shaped, hanging cones.