Common Names
aka Colorado White Fir or Rocky Mountains White Fir.

Habitat
Altitudes of 5500-11200 ft / 1700-3400 m

Description
medium to a large evergreen coniferous tree growing to 25-60 m tall and with a trunk diameter of up to 2 m. The leaves are needle-like, flattened, 2.5-6 cm long and 2 mm wide by 0.5-1 mm thick, green to glaucous blue-green above, and with two glaucous blue-white bands of stomata below. The cones are 6-12 cm long and 4-4.5 cm broad, green or purple ripening pale brown

Comments
Some consider the foliage to have an attractive scent and thus is sometimes used for Christmas decorations, including Christmas trees. Source Wikipedia. The way I remember firs, "fir is flat" the needles are flat.

Hint There is some confusion between White Fir (a true fir) and Douglas-fir (not a fir). White Fir has a strong symmetrical growth habit, meaning that the branches on limbs are opposite and when young, there is almost always a branch or limb that mirrors another. The leaves are also blueish (glaucous) and if crushed they are very fragrant. Doug-fir has a less symmetrical growth form and has alternate, rather than opposite branching. Leaves are not shiny, or glaucous, and in the southern Rockies, they are not blueish green. Also, they are not as fragrant when crushed.

Description
Abies concolor (Gord. & Glend.) Lindl. ex Hildebr., white fir, is a large forest tree from 60 to 200 feet in height that can live up to 300 years or more. Its leaves or needles are 2 to 3 inches long, silvery-blue to silvery-green, extending at nearly right angles from all sides of the twig or more or less obscurely 2- ranked; flattened, stomatiferous above and below, rounded or acute at the apex. The upright cones are 2 to 5 inches long, oblong, olive-green to purple; bracts shorter than the scales, with short, broad erose shoulders, and spikelike tips. The bark is 4 to 7 inches thick on old trunks, ashy gray and divided by deep irregular furrows in thick, horny flattened ridges; young stems with conspicuous resin blisters.

Uses
Timber: It is cut for lumber, boxes, and crates, planing mill products, sashes, doors, and general millwork and pulpwood. It is light in weight, easy to work, and relatively free from splitting when nailed; it holds nails only moderately well.

Ornamental: White fir makes an excellent Christmas tree for it has a delightful aroma, retains its needles well after cutting, and has strong sturdy branches that hold their shape. It is highly regarded as an ornamental or specimen tree in colder, moister climates.

Wildlife: White fir seed is eaten by squirrels and other rodents. Seedlings are often browsed extensively by deer. Porcupines will gnaw the bark, and grouse will feed on the buds and needles. White fir makes good winter roosting trees for grouse.

Establishment
White fir may be regenerated by natural seeding, direct-seeded, or planted. Cones begin to disintegrate and shed seeds in late September or early October, and there is a good seed crop about every 2 to 5 years. The seed germinates in the spring but usually, less than 50 percent of the seed germinate. White fir is generally rated as tolerant to very tolerant of shade so that selective (partial) cutting tends to favor this species. The initial growth rate is usually very slow up to about 30 years, then growth accelerates markedly. In planting, white fir 2 to 4-year-old stock is recommended. In direct seeding, 10 to 15 seeds per spot are recommended. To ensure adequate stocking of natural seedings, clear-cutting strips 130 to 200 feet wide or patches up to 250 feet across the largest dimension is recommended. At least 10 seed trees per acre should be left if larger areas are clear cut when adequate seedlings are not present.

Management
On better sites fully stocked, unmanaged stands of white fir may yield up to 150,000 board feet per acre at age 100. Thinning white fir stands periodically will salvage trees which would be lost to natural mortality. Pruning is not ordinarily recommended for white fir because of its tendency for epicormic sprouting and unless the tree is being grown for veneer or finish lumber, there is no need for this practice.

Young trees are easily killed by fire and must be protected from this hazard. Young sapling and pole sized trees are subject to sunscald when exposed suddenly, and thinnings should be light because of this. White fir is more prone to windthrow than ponderosa pine because of its more shallow, wide-spreading root system, and care should be taken in partial cuttings to leave buffer strips against the wind and to thin conservatively.

White fir Christmas trees require 6 to 9 years to produce a 6-foot tree. They need cultivation or other treatment to prevent excessive competition from grass. Excessive leader growth will need to be controlled by basal pruning, basal scarring, or pruning of the terminal shoot. Leader growth should be kept to about 12 inches.

Pests and Potential Problems
Some of the more important enemies of white fir are the spruce budworm, Douglas-fir tussock moth, many different bark beetles, mistletoe, and heart rot fungi. Needle rusts may be a serious problem in producing Christmas trees, and white fir is one of the conifers most sensitive to sulfur dioxide.