John Worrall

Western Larch
Larix occidentalis Nutt.

Located in the Bitterroot Mountains on 14 Sep 1805.  (Source)

Western larch is a rapidly growing, deciduous, coniferous tree which may live for more than 700 years.  Trees may reach 260 feet in height. In the Pacific  Western larch has a deep and extensive root system that provides moderate to high resistance to wind throw. Short roots are found in mineral soil more often than those of other conifers, although some are also found in decayed wood and humus. The thick bark of western larch is furrowed into large plates from which cinnamon-colored scales may flake off. The crown is relatively short, narrow, and less dense than most conifers. Young twigs are glabrous or pubescent rather than tomentose like alpine larch. The thin, light green, deciduous needles occur at the tips of short lateral spur shoots in a whorl of 15 to 30 needles on a spur. Needles on seedlings and leaders of older plants are decurrent and arranged in spirals along the stem]. The deciduous habit allows larches to avoid winter desiccation. Western larch can withstand defoliation by insects or disease better than evergreen conifers and competes well with them because its needles require less carbon to construct; it efficiently relocates nitrogen before needle fall. Its photosynthetic capacity is high, and its needles receive ample light through the open crown.

Western larch is not as tolerant of summer drought as many other conifers and is generally found on north- or east-facing slopes and other relatively moist sites. On drier sites at western larch's lower elevation or southern range limits, it is frequently unable to establish seedlings on south- or west-facing slopes, but in moist areas in the middle and northern portion of its range, it grows on all exposures. Height growth is most rapid in valley bottoms and on lower north and east slopes and poor on upper south- and west-facing slopes.  Most of the soils supporting western larch developed in glacial till or colluvium containing argillite, quartzite, and limestone bedrock, and are deep and well drained. It grows in elevations form 2,000 to 8,000 ft.

Western larch is a long-lived and highly shade-intolerant seral species. It can tolerate partial shading only as a seedling. If it is overtopped later, its crown deteriorates and it loses vigor and dies. For the first 100 years of life, larch grows faster in height than any other conifer in the northern Rocky Mountains. Since it is shade intolerant, it grows in even-aged stands, although other tree species may appear younger because they are smaller. As these stands mature, shade-tolerant conifers continue to establish and form younger understories.

Food Uses:
The sap is collected and when evaporated had the consistency of molasses or mixed with sugar to may syrup. The sweet inner bark was eaten in spring and sweet lumps of dried sap were chewed like gum. The inner bark was also dried, ground into meal, and used to extend flour. The larch sap has natural sugars that taste like bitter honey. Dried, powered larch gum was also used as baking powder. Tender young shoots can be cooked as a vegetable.

Medicinal Uses:
Larch gum was chewed and digested to relieve sore throats, internal bleeding, and enlarged or hardened livers. The gum and inner bark was used in poultices to treat insect bites, cuts, bruises, wounds, ulcers, and persistent skin problems. It was also applied externally and taken internally in teas to relieve rheumatism. Larch bark tea was taken to treat jaundice, colds, coughs, bronchitis, tuberculosis and asthma.

Other Uses:
Western larch is primarily used for construction lumber because of its strength and hardness. It makes excellent utility poles because of its length, form, and strength. It is also used in plywood manufacture and to make fine veneer. Two other wood products obtained from western larch are arabinogalactan, a water-soluble gum used industrially, and oleoresin, used to produce turpentine and related products . The wood is excellent fuel. Wood from western larch snags can be made into shakes.

Value to Animals:
Western larch stands frequently occur in areas of heavy snowpack that are unsuitable for critical winter range for big game animals. Western larch needles are a major food source for the blue grouse and spruce grouse. The red crossbill eats some western larch seed. Seed-eating small rodents prefer larger Douglas-fir and pine seed but consume some western larch seed. Squirrels cut and cache western larch cones in years when other conifers have poor crops. Western larch is browsed sparingly by elk, deer, and moose during winter when other food is scarce. Bears or porcupines may eat the inner bark of western larch saplings and poles in the spring.  Western larch appears to be unpalatable to most big game animals, but it is eaten as emergency food. Its seeds are palatable to small birds and mammals, although larger seeds are preferred.

John Worrall

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