Trees to 40m; trunk to 1.5m diam.; crown conic. Bark charcoal gray to reddish brown, scaly and deeply fissured. Twigs yellow-brown, glabrous to densely pubescent. Buds oblong, 3--4mm. Leaves 10--25(--30)mm, mostly spreading in all directions from twigs, curved toward twig apex, thickened centrally along midline, somewhat rounded or 4-angled in cross section, both surfaces glaucous, with ±inconspicuous stomatal bands; margins entire. Seed cones oblong-cylindric, 3--6 ´ 1.5--3cm; scales broadly fan-shaped, 8--l5 ´ 8--15mm, apex rounded to pointed. 2 n =24.

Coastal and montane forests to alpine slopes (where it occurs in krummholz form); 0--2400m; B.C.; Alaska, Calif., Idaho, Mont., Nev., Oreg., Wash.

The wood of Tsuga mertensiana is somewhat inferior to that of western hemlock both for building purposes and as pulp. This is a very handsome tree with its branches densely clothed with pale, spreading leaves and is adaptable to a wide variety of climatic conditions.

M.Van Campo-Duplan and H.Gaussen (1948) postulated that this taxon originated by hybridization between Picea and Tsuga . Although this is unlikely, some characteristics such as leaf arrangement and shape, phenolic chemistry, and pollen grain structure lend some support for this hypothesis.