Larix occidentalis Nutt.

Species Nomenclature

Larix occidentalis Nutt., commonly known as western larch, is a large deciduous conifer.

Mature Tree Dimensions

Mature trees reach 30 to 60 meters (98 to 197 feet) in height, with trunks up to 1.5 m (4 ft 11 in) in diameter.

Bark and Crown Shape

Their bark ranges in color from orangish to purplish brown, and they have a narrow conic crown.

Branch Structure

Main branches grow level to upswept, while side branches often droop.

Shoot Morphology

Shoots are dimorphic, divided into two distinct forms: long shoots typically 10 to 50 centimeters (4 to 20 in) long that bear several buds, and short shoots only 1 to 2 millimeters (1⁄32 to 3⁄32 in) long that hold only a single bud.

Leaf Characteristics

Its leaves are needle-like, light green, 2 to 5 cm (3⁄4 to 2 in) long, soft and very slender.

Seasonal Leaf Change

They turn bright yellow in fall, then fall off to leave pale orange-brown shoots bare until the following spring.

Seed Cone Shape and Size

Seed cones are ovoid-cylindric, 2 to 5 cm (3⁄4 to 2 in) long, with 40 to 80 seed scales.

Cone Bract Features

Each scale bears an exserted 4 to 8 mm (3⁄16 to 5⁄16 in) bract.

Cone Maturation Process

Immature cones are green to reddish purple; they turn brown when mature four to six months after pollination, and their scales open flat or reflexed to release seeds.

Old Cone Persistence

Old cones commonly remain on the tree for many years, fading to dull gray-black.

Species Longevity

Individual western larches can live for centuries, even up to one thousand years.

Largest Known Specimen

The largest known specimen is approximately 1,000 years old, 50 m (160 ft) tall, over 2 m (7 ft) in diameter, and has a 10 m (34 ft) crown; it grows at Seeley Lake, Montana.

Core Distribution Range

Western larch grows almost exclusively in the Columbia River drainage, from the east side of the Cascade Range to the west side of the Continental Divide.

Range Extent

Its range extends from near Kamloops, British Columbia, south to Weiser, Idaho, and Central Oregon.

Common Habitat Slopes

It occurs in the Blue Mountains and other ranges in southeast British Columbia and northwest Montana, and is most commonly found on moist slopes up to 1,800 m (5,900 ft) above sea level.

Elevation and Cold Tolerance

It can grow at elevations between 500 and 2,400 m (1,600 and 7,900 ft), is very cold tolerant, and can survive winter temperatures down to approximately −50 °C (−58 °F).

Soil Requirements

It only grows on well-drained soils, and cannot thrive on waterlogged ground.

Growth Rate and Shade Tolerance

Western larch grows faster than many tree species it associates with, which is a necessary adaptation because it is shade intolerant.

Fire Resistance Traits

Thanks to its thick bark, nonflammable foliage, and protective cones, the species is very fire resistant.

20th Century Fire Risk

In the late 20th century, after almost a century of wildfire suppression, larches at Seeley Lake and Glacier National Park were endangered by major fires fueled by accumulated fuel ladders; normally, smaller regular fires would have reduced this excess fuel.

Recent Fire Management

In more recent years, many smaller fires have been allowed to burn naturally.

Grouse Food Source

Grouse browse the leaves and buds of this tree.

Bird Seed Consumption

Its seeds are an important substitute winter food for some birds, most notably the pine siskin, and also including redpolls and white-winged crossbills.

Seed Use Context

This use typically happens when other preferred conifer cone seeds are in short supply.

Woodpecker Nesting Habitat

Woodpeckers make nesting openings in older specimens affected by heart rot, and these openings are later used by various small animals.

Indigenous General Uses

Indigenous peoples used the tree for multiple purposes: they applied resinous gum to injuries, chewed it to treat sore throats, and ate its cambium and sap.

Sap Collection Practice

In particular, the Kutenai and Bitterroot Salish of Montana collected the tree's sap.

Medicinal Preparations

Medicinal teas were made from the bark or foliage, and some Plateau Indian tribes drank an infusion made from young shoots to treat tuberculosis and laryngitis.

Galactan Uses

The sweetish galactan found in the sap can be processed into baking powder and medicine.

Commercial Extract Uses

A tree extract is sold commercially as a health supplement.

Arabinogalactan Applications

Its water-soluble arabinogalactan is used in food, medicine, ink, and paint.

Wood Physical Properties

The wood is tough, durable, and flexible when cut into thin strips.

Yacht Building Use

It is highly valued for yacht building, as yacht construction requires knot-free wood that can only be obtained from old trees pruned when young to remove side branches.

Rustic Fencing Use

Small larch poles are widely used for rustic fencing.

Firewood Common Name

The wood is very popular as firewood in the Pacific Northwest, where it is often called "tamarack", even though it is a separate species from tamarack larch.

Firewood Burning Characteristics

It burns with a sweet fragrance and a distinctive popping noise.

Turpentine Production

Western larch is also used to produce Venice turpentine.