Scientific name: Larix occidentalis T. Nuttall 1846

Synonyms: Larix americana var. brevifolia Carrière, Pinus nuttallii Parl.

Common names: Western larch

Description

Tree to 50(-70) m tall, with trunk to 1.5(-2.3) m in diameter. Bark reddish brown and smooth at first, becoming scaly and finally breaking up into irregular, flat-topped gray ridges separated by reddish furrows. Crown narrowly cylindrical, with numerous short horizontal branches above a straight, clear trunk. New branchlets orange-brown, hairy at first, becoming hairless during the first summer. Buds small, about 3 mm long, dark brown, resinous, those of spur shoots fuzzy. Needles of spur shoots straight, (12-)25-35(-45) on each spur, soft, (1.5-)2.5-4(-5) cm long and 0.5-0.8(-1) mm wide, pale green, turning brilliant orange-yellow in autumn before falling. Midrib raised beneath and with a few lines of stomates in a narrow band on either side. Pollen cones cylindrical, yellowish brown, about 8-15 mm long. Seed cones oblong, (2-)2.5-4.5(-6) cm long, with (30-)40-60 seed scales, green with a reddish tinge before maturity, ripening reddish brown, on a gently curved, coarse stalk (2.5-)4-12 mm long. Seed scales roundly triangular, the tip slightly notched, straight or curled back at maturity, fuzzy on the inner face. Bracts often curled back, 1-2 cm long, about as long as the seed scales, elongately triangular and tipped by a bristle that extends about 1 cm beyond the seed scale, pale against the darker seed scales. Seed body 3-4 mm long, without resin pockets, the firmly clasping wing another 6-10 mm longer.

Both the common and scientific names (Latin for “of the west”) reflect the discovery of this species in western North America long before the discovery of subalpine larch.

Pacific Northwest of North America east of the Cascade Range, in southeastern British Columbia and southwestern Alberta and in eastern Washington, northeastern Oregon, northern Idaho, and northwestern Montana. Usually mixed with other conifers though often making up the majority of a stand on deep soils of gentle mountain slopes, flats, and valleys; (400-)600-1,600(-2,100) m.

Conservation Status

Red List Category & Criteria: Least Concern

This widespread and common species is assessed as Least Concern, due to its broad distribution, ready recruitment of seedlings and regeneration power after disturbance. As a seral species readily colonizing open ground after disturbance, its initial numbers on a site can be very high, later to diminish as forest succession progresses.

Larix occidentalis occurs in the mountains, at elevations between 600 m and 2,100 m a.s.l., usually on grey brown, well drained podzolic mountain soils, which are moderately acid. The climate is cold, with cool summers and moist winters, the annual precipitation ranges from 450 mm to 875 mm, much of it falls as snow. It may occur in pure stands; in an initial stage after disturbance (e.g. fire) Pinus contorta var. latifolia can become dominant, followed by Pinus ponderosa in certain areas; later in the succession Pinus monticola, Pseudotsuga menziesii, Abies grandis and Abies lasiocarpa, finally Thuja plicata and Tsuga heterophylla take their place. Picea engelmannii and Tsuga mertensiana occur mainly above Larix occidentalis and may be associated with Larix lyallii.

Western larch is an important timber tree. It can grow to great size with straight boles and grows rapidly in height though it takes longer to increase in girth. The wood is durable, hard and strong and used for long poles, railroad sleepers, mine timbers, fine veneer, and pulpwood for the paper industry. The resin from the wood has useful water soluble properties for a variety of industrial products especially applied in ink, paint and offset lithographic printing. The use of this species in amenity planting is limited, although some provenances should grow well in cooler climates.

This species is present in several protected areas, while as a valuable timber tree it is encouraged to (re-)grow in montane forests managed as a timber source.

References

Farjon, A. (2010). A Handbook of the World's Conifers. Koninklijke Brill, Leiden.
Eckenwalder, J.E. (2009) Conifers of the World: The Complete Reference. Timber Press, Portland.
IUCN Red List of Threatened Species, International Union for Conservation of Nature and Natural Resources. Cambridge, UK /Gland, Switzerland