Abies lasiocarpa Seeds | Subalpine Fir
LATIN NAME: Abies lasiocarpa
COMMON NAME: Subalpine Fir
Plant Profile
Abies lasiocarpa is the fir of the timberline, and it is the narrowest conifer in the western mountains. The crown is a steeple of short, upward-sweeping branches, often no more than three metres wide at the base and fifteen metres tall, and on an exposed ridge it can be a shrub a metre high that is a century old. The needles are blue-green, blunt, and point upward from the twig rather than lying flat.
The species grows from Alaska to Arizona, usually above 1,500 metres and up to the tree limit, on deep snowpack and cool, moist soil. The bark is smooth and grey with resin blisters, and on old trees at high altitude it becomes thick and corky, which is why one form is sold as corkbark fir. The cones are upright, dark purple, and they break up on the tree in autumn.
Science & Biotechnology
The species is a classic example of adaptation to deep snow. Its narrow crown sheds snow rather than holding it, and the branches are flexible enough to bend under a load that would break a spruce. At timberline the tree reproduces mainly by layering, sending roots from lower branches that are buried by snow, because a seedling has little chance of surviving the winter.
Corkbark fir, variety arizonica, has a thick, pale, corky bark that insulates the cambium against cold and against fire. The variety is recognised by the bark and by the pale needles, and it is the form most often planted in gardens, since the typical subalpine fir is a poor performer at low altitude. The two intergrade where their ranges meet, which makes the taxonomy a matter of argument.
Uses & Benefits
The wood is light, soft and not very strong, and it is used for pulp, for boxes and for light construction. It is not a preferred timber, and the tree is cut mostly as part of mixed stands. The species is grown as an ornamental for the narrow blue crown, and corkbark fir is a collector’s plant in Europe and in the eastern United States.
The resin was used as a wound dressing and as a chewing gum by several peoples of the interior north-west, and the boughs were used for bedding and for shelter. The tree is also cut in small numbers for Christmas trees, though it is slower and less uniform than the noble fir.
Growing from Seed
Subalpine fir sheds its seed dormant, and it takes a long cold spell to break that. Stratify at 4 degrees for eight weeks, then sow on a free-draining mix at 18 degrees; germination is in three to five weeks. The seedlings are slow and should spend two years in a nursery bed before planting out, since they transplant badly once the taproot has run.
The tree wants a cool, humid site with deep, acid soil, and it fails in heat and in drought. It is hardy to about minus forty, which is not the problem; the problem is summer. Plant it in a north-facing slope or in a site with cool nights, mulch heavily, and keep grass away from the trunk. It is not a tree for a warm, dry garden.
Our Take
A timberline spire for a cold, damp site, and the corkbark form for anyone who wants a blue fir that stays small.
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