PNW Native
Ranges along West Coast from Alaska to Northern California
Western hemlock grows up to 60 m / 180 ft tall and is easily-identified by its hook-shaped drooping lead and downward-drooping thin branches covered in lacy needles arranged in irregular flat sprays. Ends of needles are blunt, lengths are uneven in the range of 5 – 20 mm in length, and topsides are yellow-green with a white stomata-lined underside. Bark is smooth when young but develops into grey-red-brown scaly and furrowed bark. Pollen cones are numerous and small. Seed cones are numerous, small, purple when young maturing to brown and woody, and abundant in forest floors. (PM)
Western hemlocks are widely used by numerous animals for browse, cover, nesting sites, and thermal protection. In coastal WA, OR, and BC, black-tailed deer and Roosevelt elk widely browse western hemlock foliage. Black bears use pole-sized western hemlocks as scratching posts and can damage saplings utilizing them in this manner while stripping the trees of bark. Grizzly bears in the Selkirk Mountains of northern ID, northeastern WA, and southern BC are known to dwell in densely-packed western hemlock forests. Mountain beaver clips off branches and stems and girdles the bark of western hemlock saplings. Snowshoe hare and rabbit also graze the foliage, biting off the main stems of western hemlock seedlings. At a site studied in the Oregon Cascades, deer mice ate about 22% of western hemlock seeds fallen to the forest floor. In the western Oregon Cascades, northern flying squirrel and red tree vole reside in western hemlock canopies amongst other small mammals. Cavity-nesting birds like the yellow-bellied sapsucker and the northern three-toed woodpecker readily inhabit western hemlock trees. The largest barred owl population in BC resides in the Columbia Forest Biotic Area, where western red-cedar and western hemlock are the dominant climax species. The endangered and well-loved northern spotted owl resides often in old-growth forests dominated by Douglas-fir and western hemlock in WA and OR. (Te)
Western hemlock is very common at low-middle elevations and is highly shade-tolerant. It grows from dry to wet sites and is adapted to grow on nurse logs, humus, decaying wood, and mineral-rich soil. (PM) Unlike other conifers like Sitka spruce, coast redwood, and Douglas-fir, which rely on ecological disturbance to clear understorey for the next generation, great size, longevity, and limiting seed production to avoid seed predators, western hemlock relies on shade tolerance, prolific fast growth, the ability to form a thick understorey sapling layer, and copious seed production to overtake longer-lived and larger trees as a dominant species in PNW forest ecological succession. Western hemlock trees drop more than 1 seed cone per square inch under the tree. These seeds are almost entirely dependent on decaying wood for their development into trees. Young western hemlock stands along the Oregon coast produce the fastest-growing biomass ever measured. Western hemlock forests are more densely packed with trees than forests of other conifer species. The mechanism that allows these trees to grow so rapidly and abundantly with relatively little sunlight is a sheer abundance of needles – a western hemlock tree with a diameter of 6 inches can support over 10,000 square feet of leaf surface area, which is almost double the leaf surface area of Douglas-fir. Unfortunately, there is a trade-off to this adaptation: the high leaf surface area facilitates high volumes of transpiration, leading to a large amount of lost moisture. The same adaptation that grants western hemlock shade tolerance also makes it susceptible to drought, a classic example of an evolutionary trade-off. The shallow roots and thin bark of western hemlock makes it susceptible to heart rot, wind, and fire. Indian Paint fungus, a basidiomycete shelf fungus, causes heart rot in western hemlocks, which causes most trees at lower elevations to be hollow by 200 years old, and causes the tree to snap in half, clearing a section of forest overstorey for the next generation of trees to prosper in. Western hemlocks at higher elevations are less prolific, but the cold inhibits the heart rot causing fungus, leading to much older western hemlocks. (DM)
Hemlock looper, a moth caterpillar, is the only natural pest of the western hemlock, and it typically only affects local stands severely without widespread blight. Warm summers that stretch into dry Septembers are correlated with hemlock looper outbreaks, which is the season where the moth reaches reproductive maturity and its preferred conditions. (DM)
Due to its abundance, western hemlock was widely used in various ways by Northwest Coast Peoples. Hemlock bark naturally has a high tannin content and was therefore used as a pigment, cleansing, and tanning agent. (PM) The S’Klallam, Makah, Lummi, Chehalis, and Snohomish all make a red-brown dye from the bark. The Makah preparation involved pounding the inner bark and boiling it in saltwater. This dye was then turned into a red-hued paint applied to paddles and spears with the apparent effect of helping preserve the wood. It was believed by some that placing the painted paddles over a fire would enhance the preservative powers of the paint. The Makah also used hemlock boughs as underwater rakes to collect herring eggs. The Chehalis among other tribes dyed their fishing nets red-brown with western hemlock, making the nets invisible to salmon. (EG) The Quinault made an orange-yellow paint with mashed hemlock bark and salmon roe, which they used to color paddles and dip-nets. (PM) The Quinault also made a lining for cooking pits from large bark strips sewn together, and a basket they used to store elderberries. The Quinault used western hemlock boughs as a temporary hunting shelter. The Quileute made a waterproofing agent for their spruce baskets from finely-chopped hemlock bark boiled and made into a juice. They also used western hemlock to tan hides. The Skagit, Snohomish, and Quinault would use young western hemlock trees to pole canoes upstream, the Quinault used western hemlock as the walk across the top of their fish weirs, the Snohomish would use young saplings as anchors for fish traps spread across a stream, the Lummi used hemlock as poles for dip-nets, and the Skagit also used western hemlock in fish trap construction. The wood is primarily used as firewood by the Quinault and Chehalis. (EG) The heavy, durable wood of western hemlock is easy to carve, and spearshafts, children’s bows, roasting spits, elderberry-picking hooks, dip-net poles, wedges, combs, and spoons were carved from the wood. (PM)
Applying hemlock pitch to the face was widespread among Northwest Coast Peoples, either as a face paint or chapping inhibitor. The Makah used hemlock pitch to prevent sunburn. The Makah also applied the pitch to hair to remove lice and fleas. Powdered hemlock bark mixed with oil was used for the same purpose. The Makah chewed western hemlock bark and applied it to wounds as a coagulant. A hemlock decoction is drunk by the Makah to treat internal injury. The Quinault would mix western hemlock pitch with elk tibia marrow and apply to the eyebrows as a cosmetic. Hemlock bark was boiled by the Quinault to create a laxative, while the same infusion was used by the Skagit and Cowlitz as a wash for sore skin and eyes and is also believed to stop internal hemorrhage. The S’Klallam uses a similar preparation with licorice fern to boost the anti-hemorrhaging capacity of the infusion. The Skagit pounds the bark and boils it as a sore throat treatment, and the Chehalis use the same tea as a treatment for syphilis and tuberculosis. (EG)
Western hemlock is widely-regarded as a useful all-purpose timber for wood products, and it is commonly made into pulpwood, paper, and paperboard products. The majority of alpha-cellulose used in synthetic textile production including rayon, cellulose, and certain plastics are sourced from western hemlock trees. Mine timber, railway ties, general construction, marine pilings, interior finishes, kitchen cabinets, gutter stock, flooring and ceiling, plywood veneer, boxes, crates, and general construction are also made out of western hemlock. (Te)
[1] Tesky, Julie L. 1992. Tsuga heterophylla. In: Fire Effects Information System,. U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory (Producer). Available: https://www.fs.fed.us/database/feis/plants/tree/tsuhet/all.html.
