In the pine family, true fir trees (genus Abies) include 11 species native to North America. All firs are characterized by short, mostly soft needles that are blunt-tipped and do not leave a raised scar on the twig (characteristic of spruces). Their cones are upright and only grow on the highest branches of the tree. Firs are narrow in shape and have rigid upright or horizontal branching that never droops as some spruces trees do. Identification is dependent on examination of the needles, cones and range, and is always best if compared with pictures in a field guide.
Subalpine Fir and Rocky Mountain Fir are very similar in appearance; both evergreens grow from 30 to 60 feet tall and are similar in looks and aroma to the Balsam Fir, but are very narrow. Rocky Mountain Fir tends to have shorter needles and one of the main differences between the two is the bark (reddish in Subalpine and light brown in Rocky Mountain). Noble Fir (Abies procera), also called the Oregon Larch, grows up to 295 feet tall, though usually around 200 feet. It has a pointed top with stiff horizontal branches and a slight turpentine-like odor. The cones grow up to 5 inches tall, are greenish-red with obvious bracts and needles are on branches in four-sided formation. The Grand Fir (Abies grandis) grows to 297 feet tall and older trees have a rounded top. Cones are smooth, green or blue-grey and short (2.5 inches). It grows in United States Department of Agriculture zones 4 through 7. Pacific Silver Fir (Abies amabilis) is often 60 to 90 feet tall, though it can grow to 245 feet, and has dense dark green branches and crown. Cones are 4 inches tall and very dark green to purplish. It grows in zones 5 and 6.
West Coast to Southwest
California Red Fir is common in the mixed coniferous forests, often at high elevation in northern California. It is 80 to 120 feet tall, though can grow to be over 250 feet, has a camphor-like odor and has large (7-inch) cones that are dark brown to green. Needles are 1 inch long. The Sierra White Fir (Abies lowiana) is a medium to large evergreen (maximum height 246 feet), has a pine-like odor, and 3-inch olive green, smooth cones. It grows in mixed mountain coniferous forests mostly in California. The Colorado White Fir (Abies concolor) grows to 110 feet, has longer, more sparsely spaced needles than most firs at 2 inches, and very green cones that grow to 4 inches. These grow mostly in zones 4 through 7 in the west to southwest region, the highest concentration being in New Mexico, Nevada, Utah, Arizona and Colorado. The Bristlecone Fir has the most distinct cones of all true firs, as they are short (3.5 inches), oval, greenish-purple, with 2-inch spiky bracts bristling out in all directions. The needles on the branches are sharply pointed as well. According to tree expert David Allen Sibley in his book "The Sibley Guide to Trees," it is a rare tree found mostly in moist canyon bottoms in the Santa Lucia Mountains in California.
Balsam Fir (Abies balsamea), also known as the Balm-of-Gilead, is a small to medium evergreen (40 to 60 feet tall) favored as a Christmas tree because of its aromatic, spicy-scented resin. It is common in moist woodlands, swamps, boreal forest in zones 3 to 5 and is also commonly cultivated on tree farms. Its needles are about 3/4 inches in length, blue-green in color with a paler underside. The cones grow to 3 inches long, are grayish-purple or purple-green and have a smooth oval form.
Known as the Southern Balsam Fir, the Fraser Fir (Abies fraseri) is a small to medium evergreen (30 to 60 feet tall). It looks similar to the Balsam Fir except for the have longer, projecting bracts on the cones, making them look spiky instead of smooth. Also the cones are about 2 inches, an inch shorter than the cones of Balsam Fir. These are rare and declining in the wild in mountaintop forests according to David Allen Sibley. They are also commonly grown for the commercial Christmas tree market, however.
Douglas-firs were classified as spruces, firs or hemlocks before finally being classified in their own genus, but commonly come to mind when discussing fir trees. Types include bigcone Douglas-fir, common Douglas-fir and "Rocky Mountain" common Douglas-fir. Other true fir trees that are not native to North America include European Silver Fir, Nikko Fir and Caucasian Fir, which are native to central and southeastern Europe but were introduced to North America.