The Larch

Western Larch by Highway 35

We usually think of conifers as evergreen trees, and most conifers are evergreen. However, some conifer species are notable exceptions. They are deciduous. That is, they drop their needles in the fall and grow a new crop each spring. Most of these deciduous conifers are larches. Ten species of larch grow in the Northern Hemisphere, three are native to North America, and two grow in the Pacific Northwest. Western Larch (scientific name, Larix occidentalis) is the most common larch in the Northwest and the only larch native to Oregon. You may not notice the larches on your summer hikes in the Cascade Mountains, but in November, when the needles turn golden-yellow, they stand out like trees on fire. You can see them along Oregon Highway 35 north of Mount Hood Meadows.

Now, you may wonder, why do larches drop their needles in the fall? Other conifers growing nearby seem to survive the winter cold just fine with their needles intact. These conifers have adapted to the cold by moving water out of the cells in the needles, leaving a concentrate that acts like antifreeze, or by purifying the water in the cells so ice crystals can’t form even at temperatures well below freezing. The larches have adapted a completely different strategy. They just drop their needles in the fall and grow new ones in the spring. This enables larches to survive some of the coldest temperatures of any of the conifers, growing high in the mountains and in the northern latitudes of North America and Siberia.

Western larch

It takes a lot of energy to grow new needles every year. However, since the needles only have to last one season, they don’t need to be strong and durable. So less energy is needed to grow them. As a result, you will notice that larch needles are much more delicate than those of evergreen conifers. The same is true of the leaves on trees. Note how the evergreen leaves are thick and stiff compared to the delicate leaves on deciduous trees.

Western larch needles

Larches are easy to identify. The needles grow in bundles like a pine with about 25 needles in each bundle. In the Cascades, Western Larch grows mostly on the east side of the Cascade summit at elevations up to 6000 feet. It also grows in the mountains of northeastern Oregon and Washington, and in northern Idaho and western Montana.

Alpine larch (Larix lyallii) grows at elevations higher than Western Larch, near the timberline in the North Cascades in Washington. It also grows in the Rocky Mountains of Idaho, Montana, and Canada. 

Western larch is an important timber tree. The wood is nearly as strong as Douglas fir and is used for framing and finishing. Western larch is also a popular firewood in the Northwest. It is often called “tamarack” by wood cutters, a common name for the other North American larch (Larix laricna), which grows in the northeast United States, across Canada, and in central Alaska.

Japanese larch at Hoyt Arboretum

November is the time of the year to look for larches, when they display their fall colors. To see the larches at Hoyt Arboretum in Portland, start at the Visitor Center and walk west on the Fir Trail.

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See Also
  
Fall Conifer Colors
How Do Conifers Survive the Cold?
Western Larch at Northwest Conifers