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Alaska’s most common forest tree and Washington’s state tree, the western hemlock populates the Coast and Cascade Ranges as a champion understory tree. In fact, it can remain in the shade of larger trees for decades, just waiting to take advantage of a break in the tree cover.
Western Hemlock (Tsuga heterophylla)
Distribution
The western hemlock ranges from Alaska to northern California. In Oregon, it is seen both in the Coast and Cascade ranges, but is especially numerous in the Coast range, where rainfall is plentiful. There have been reports of western hemlocks living up to 1200 years in their native range.
Needles, Cones, Bark
The needles are not a uniform size but are all small (.7 to 2 cm). They attach in a spray pattern around the stem, giving the hemlock a fluffier look than other conifers. Older tree branches droop dramatically. A good identification tip is to look for the western hemlock's top branch drooping against the skyline.
The cones don’t appear on the hemlock until the tree is about 25 years old. The small, one-inch cones are green when immature, and change from a rosy red to brown as they age. They are often numerous enough to cover the ground under the tree.
When young, the bark of the western hemlock is smooth and grey but soon becomes rough and deeply furrowed with age. The bark can be mistaken for that of a Douglas fir, so be sure to use other markers to identify an unknown tree.
Indigenous Peoples and Western Hemlock
Many tribes find the western hemlock extremely useful. Because of its high tannin content, the bark is used by many as a tanning agent or dye. The Nuxalt and Chehalis, for example, use the hemlock to dye their fishing nets brown, making them invisible to fish. Western hemlock boughs make excellent bedding. Kwakwaka’wak’w dancers use the soft boughs for skirts, headdresses, and headbands. The western hemlock also offers its services as a food source, carving wood, medicine, and more.
Western Hemlocks in Portland
Western hemlocks are scattered around Portland here and there. The best places to go to see western hemlocks are our city parks. The biggest specimens are at Farragut Park in N Portland and Laurelhurst Park in SE Portland.
Heritage Trees
There are currently no western hemlocks designated as Heritage Trees by the City of Portland. If you know of an outstanding western hemlock or other amazing tree, consider nominating it for Heritage Tree status. Not only will the tree be recognized as an important part of the community, but it will also be protected for years to come.
Caring for Western Hemlock
Western hemlocks are one of our most shade tolerant trees. They can live for decades in dense shade, making it perfect for dark corners. It must, however, receive adequate moisture. Eventually, your western hemlock will need space to grow up (way up) and out.
Don’t forget to mulch in the summer to help the roots and soil stay moist and cool. See Urban Forestry's establishment care guide.
Problems and Pests: Typically, western hemlocks are hardy trees. Hemlock woolly adelgid is an insect that causes concern for eastern hemlocks, but western hemlocks seem to have better immunity to these pests and are home to predators that prey on the woolly adelgid.
Western hemlocks are rarely bothered by disease.
Use Oregon State University's plant disease and insect management handbooks to diagnose potential problems with your western hemlock.
- Host and Disease Descriptions | Pacific Northwest Pest Management Handbooks (pnwhandbooks.org)
- Search Insect Handbook | Pacific Northwest Pest Management Handbooks (pnwhandbooks.org)
For More Information
- Tsuga heterophylla - Wikipedia
- Tsuga heterophylla (Raf (usda.gov)
- Tsuga heterophylla | Landscape Plants | Oregon State University
- WESTERN HEMLOCK (usda.gov)
- Tsuga heterophylla - Trees and Shrubs Online
- Pojar, Jim and Andy MacKinnon, Plants of the Pacific Northwest Coast (Revised), 2004, Lone Pine Press.