Tsuga heterophylla, the western hemlock[2] or western hemlock-spruce,[3] is a species of hemlock native to the northwest coast of North America, with its northwestern limit on the Kenai Peninsula, Alaska, and its southeastern limit in northern Sonoma County, California.

[5] T. heterophylla is an integral component of Pacific Northwest forests west of the Coast Ranges, where it is a climax species.

[9] The species is closely associated with temperate rainforests, and most of its range is less than 100 kilometres (62 miles) from the Pacific Ocean.

[6] The species can also be found in humid areas of mountains further inland, where western white pine is normally dominant.

[6] At higher elevations, the species can be found mingling with T. mertensiana (mountain hemlock), seeming to take on some of its characteristics although there is no hard evidence of hybridization.

[6] Western hemlock forms ectomycorrhizal associations with some well-known edible fungi such as chanterelles (Cantharellus formosus, C. subalbidus, and Craterellus tubaeformis).

[12] Older forests are damaged by rot-causing fungi, dwarf mistletoe, and leaf-consuming insects such as Acleris gloverana and Lambdina fiscellaria.

[6] Western hemlock is cultivated as an ornamental tree in gardens in its native habitats and along the U.S. Pacific Coast, where its best reliability is seen in wetter regions.

It needs a high level of organic matter (well-rotted wood from an old log or stump is best; animal manures may have too much nitrogen and salt), in a moist, acidic soil.

Until the early 1920s, the tree was largely ignored for use as lumber due to its presumed similarity to the poor-quality eastern hemlock.

This practice originates from traditional gathering methods used by Native Alaskans from southeast Alaska, specifically the Tlingit people.

[citation needed] Tender new-growth needles can be chewed directly or made into a bitter tea, rich in vitamin C (similar to some other hemlock and pine species).