Western Larch-Larix occidentalis is a species of larch native to the mountains of western North America, in Canada in southeastern British Columbia and southwestern Alberta, and in the United States in eastern Washington, eastern Oregon, northern Idaho and western Montana.
It is a large deciduous coniferous tree reaching 30-60 m tall, with a trunk up to 1.5 m diameter. The crown is narrow conic; the main branches are level to upswept, with the side branches often drooping. The shoots are dimorphic, with growth divided into long shoots (typically 10-50 cm long) and bearing several buds, and short shoots only 1-2 mm long with only a single bud. The leaves are needle-like, light green, 2-5 cm long, and very slender; they turn bright yellow in the fall, leaving the pale orange-brown shoots bare until the next spring.
The cones are ovoid-cylindric, 2-5 cm long, with 40-80 seed scales; each scale bearing an exserted 4-8 mm bract. The cones are red when immature, turning brown and the scales opening flat or reflexed to release the seeds when mature, 4-6 months after pollination. The old cones commonly remain on the tree for many years, turning dull gray-black.
It grows at 500-2,400 m altitude, and is very cold tolerant, able to survive winter temperatures down to about −50 °C. It only grows on well-drained soils, avoiding waterlogged ground.
The seeds are an important food for some birds, notably Pine Siskin, Common Redpoll and White-winged Crossbill.