It is a medium-sized evergreenconifer growing to tall, exceptionally to tall, with a trunk up to across, and a very narrow conic crown. The bark on young trees is smooth, gray, and with resin blisters, becoming rough and fissured or scaly on old trees. The leaves are flat and needle-like, long, glaucous green above with a broad stripe of stomata, and two blue-white stomatal bands below; the fresh leaf scars are reddish. They are arranged spirally on the shoot, but with the leaf bases twisted to be arranged to the sides of and above the shoot, with few or none below the shoot. The cones are erect, long, dark blackish-purple with fine yellow-brown pubescence, ripening brown and disintegrating to release the winged seeds in early fall.
Taxonomy
There are two to three taxa in subalpine fir, treated very differently by different authors:
The Rocky Mountains subalpine fir is very closely related and of disputed status, being variously treated as a distinct species Abies bifolia, as a variety of Coast Range subalpine fir Abies lasiocarpa var. bifolia, or not distinguished from typical A. lasiocarpa at all. It occurs in the Rocky Mountains from southeast Alaska south to Colorado. It differs primarily in resin composition, and in the fresh leaf scars being yellow-brown, not reddish. The Flora of North America treats it as a distinct species ; the USDA includes it within A. lasiocarpa without distinction.
The corkbark firAbies lasiocarpa var. arizonica occurs in Arizona and New Mexico. It differs in thicker, corky bark and more strongly glaucous foliage. In resin composition it is closer to A. bifolia than to typical A. lasiocarpa, though the combination "Abies bifolia var. arizonica" has not been formally published. The Flora of North America includes it within A. bifolia without distinction; the USDA treats it as a distinct variety of A. lasiocarpa.
The bark is browsed by game animals and its leaves are eaten by grouse. Songbirds, Richardson's grouse, Cascade pine squirrels, and other mammals consume the seeds.
Uses
The wood is used for general structural purposes and paper manufacture. It is also a popular Christmas tree. It is a popular ornamental tree for parks and large gardens, grown for its strongly glaucous-blue foliage. The cultivarAbies lasiocarpa var. arizonica 'Compacta' is suitable for smaller gardens, growing as a shrub to tall by broad. In the UK It has gained the Royal Horticultural Society's Award of Garden Merit. Some Plateau Indian tribes drank or washed in a subalpine fir boil for purification or to make their hair grow.
