It is a large deciduousconiferous tree reaching tall, with a trunk up to diameter. The largest known western larch is tall and in circumference with a crown, located at Seeley Lake, Montana. 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 and bearing several buds, and short shoots only long with only a single bud. The leaves are needle-like, light green, long, and very slender; they turn bright yellow in the fall, leavingthe pale orange-brown shoots bare until the next spring. The seed cones are ovoid-cylindric, long, with 40 to 80 seed scales; each scale bearing an bract. The cones are reddish purple when immature, turning brown and the scales opening flat or reflexed to release the seeds when mature, four to six months after pollination. The old cones commonly remain on the tree for many years, turning dull gray-black. It grows at elevations between, and is very cold tolerant, able to survive winter temperatures down to about. It only grows on well-drained soils, unable to thrive on waterlogged ground. The seeds are an important food for some birds, notably pine siskin, redpoll, and Two-barred crossbill. In autumn, the foliage frequently turns yellow before it falls off.
Uses
Some Plateau Indian tribes drank an infusion from the young shoots to treat tuberculosis and laryngitis. The wood is tough and durable, but also flexible in thin strips, and is particularly valued for yachtbuilding; wood used for this must be free of knots, and can only be obtained from old trees that were pruned when young to remove side branches. Small larch poles are widely used for rustic fencing. Western larch is used for the production of Venice turpentine. The wood is highly prized as firewood in the Pacific Northwest where it is often called "tamarack," although it is a different species than the tamarack larch. The wood burns with a sweet fragrance and a distinctive popping noise. Indigenous peoples used to chew gum produced from the tree as well as eat the cambium and sap. The sweetish galactan of the sap can be made into baking powder and medicine. Grouse browse the tree's leaves and buds.
