Fir trees comprise their own botanical genus named Abies. There are about 50 different species of firs worldwide, all native to cooler northern or montane areas of the northern hemisphere. They do not flower but produce cones in very early summer that ripen and break apart by winter. The Fraser fir (Abies fraseri) boasts particular favor at Christmastime for use as cut trees, since it retains its needles quite well.
Fir trees belong to the pine family, Pinaceae. In 1753, Linnaeus, the renowned botanist and father of modern taxonomy, grouped fir trees into the same genus as spruces and pines. He assigned them all the genus name Pinus. A year later the botanist Miller segregated fir trees into their own genus, Abies, which remains today. Pines are known as Pinus, while spruces are Picea.
These evergreen trees grow into tall, upright plants with a slender, pyramidlike shape. Their branches occur in whorls around the trunk. The needles are short and flattened and are flexible, making them soft to the touch. Usually on the needles there are two silvery bands on the undersides. In the uppermost branches the bluish purple female cones develop in late spring; the pendent male cones dapple branch tips all over the upper half of the tree and are green when young. After pollination by the wind, the male cones drop away and the female cones mature to shades of brown, split apart and release seeds by the end of autumn. Needles persist 5 years or more before dropping.
Aging the Tree
The growth on firs each year develops with regularity. On the tree trunk, a whorl of branches radiates anew each year, so that by counting the tiers of branches you can estimate the age of the fir. On the branches, each growing season creates two side branches and an elongating terminal shoot. Therefore, by counting the number of paired side shoots on a branch, you can age and trace its development back from the current season's growth tip.
Faster growing in general than pines or spruces, fir trees tend to frequent fertile soil regions. The soils are moist but well draining and are not alkaline in pH (7.2 and lower). They prosper in full sun exposures and tend to look their best growing in regions with cooler summers. They require a prolonged winter dormancy with cool to very cold temperatures, depending on the exact species.
Fir trees in North America find extensive use as pulpwood and lumber and Christmas trees where they are cultivated in commercial fields. They are also grown as ornamental specimen plants or used for windbreaks and large-scale screening. Firs frequently have a pleasant odor when their foliage or tender twigs are crushed. It has been used as a stuffing material for pillows. Oils extracted from firs help fragrance commercial products labeled "pine scented," according to The Gymnosperm Database.