General: Pine Family (Pinaceae). Native, evergreen trees growing to 20 meters tall with a sharp, spire-like crown, the upper several feet often less than 30 cm in diameter, the plants often reduced to a prostrate shrub on exposed sites near timberline. Bark is smooth, grayish-white, with resin blisters, becoming furrowed only when the tree approaches a foot in diameter (or var. arizonica, see below, with a softer, corky trunk); branches with bark splitting to reveal a reddish-brown layer; leaf scars with periderm red (or tan in var. arizonica). Needles are 1.8-3 cm long, flattened, grooved and bluish-green waxy on the upper surface, 1-ranked and tending to turn upward so that the foliage of a particular branch appears flattened and as though no leaves were attached to the lower sides of the twigs; resin canals median, located between the upper and lower epidermis. Seed cones are 6-12 cm long, 2-4 cm wide, dark purple, erect and only on the uppermost branches. The common name refers to the distribution of the species in the subalpine zone.
Variation within the species: Taxonomy of the species is not settled. Abies bifolia A. Murr. may be treated within A. lasiocarpa or as a separate species (evidence summarized by Hunt 1993). A southern population system (Arizona, New Mexico, Colorado) is sometimes recognized as A. lasiocarpa var. arizonica (Merriam) Lemmon (corkbark fir), or it may be identified as part of A. bifolia.
Abies lasiocarpa in the broad sense is distinguished from A. balsamea by 4-5 stomatal rows on the upper surface at midleaf (vs. mostly 7 rows in A. balsamea).
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