Ecological Restoration Specialists

Western Hemlock – Tsuga heterophylla

TSHE drawing 3

PLANT OF THE MONTH

Tsuga heterophylla
(Western hemlock)

The western Hemlock is easily identifiable by its drooping, conical top and similarly drooping branches. It ranges from 165 to 230 feet in height, and can reach up to 9 feet in diameter. Its needles are flat, short, and rounded, and their dark green top surfaces contrast with the bottom surface, which is dominated by two white parallel stripes. These needles are arranged in a spiral, but twist around at the base in order to form two flat rows. The hemlock is monoecious, meaning that it has male and female cones- male cones are small, yellow, and appear at the bases of needles, whereas female cones are purple, brown when they mature, and situated terminally on branches.
Preferring high humidity and precipitation, the Western Hemlock tends to grow near the Pacific coast, and its native range reaches from the northern end of California to the southern tip of Alaska. It can be found in a range of elevations, from sea level up to 7000 feet. Seedling growth starts out very slow, and young plants often grow from nurse logs and other coarse woody debris. Because of the species’ tolerance for shade, these hemlocks are able to establish themselves under a thick canopy until a gap can be exploited, which leads to rapid growth and the shading out of other less-shade tolerant plants. This makes the species a late-succession specialist, which thrives in areas where fires, which would restart succession, are actively suppressed by human intervention. In addition, these trees are long lived, with recorded individuals of up to 1200 years.
The Western Hemlock has been used in the timber industry, which is a major reason for its introduction to temperate areas outside of its native range, such as the eastern United States and western Europe. Its cambium is edible, and fresh needles can be brewed to make a bitter but vitamin c-rich tea. The tree also forms ectomycorrhizal relationships with edible fungus, such as several chantrelle species, so it’s a good one to keep an eye out for while mushroom hunting.
For current availability of Western hemlock, click here.