Tsuga heterophylla
pruche de l'ouest, western hemlock
gray-brown, scaly and moderately fissured.
yellow-brown, finely pubescent.
ovoid, gray-brown, 2.5–3.5mm.
(5–)10–20(–30)mm, mostly appearing 2-ranked, flattened;
abaxial surface glaucous with 2 broad, conspicuous stomatal bands, adaxial surface shiny green (yellow-green);
margins minutely dentate.
cones ovoid, (1–)1.5–2.5(–3) × 1–2.5cm;
scales ovate, 8–15 × 6–10mm, apex round to pointed.
=24.
Tsuga heterophylla
Tsuga heterophylla is a dominant species over much of its broad distributional range. It has become the most important timber hemlock in North America. The wood is superior to that of other hemlocks for building purposes and it makes excellent pulp for paper production.
Tsuga × jeffreyi (Henry) Henry was described from southwestern British Columbia and western Washington as a hybrid between T. heterophylla and T. mertensiana. Hybridization is rare, if it occurs at all, and it is therefore of little consequence (R.J. Taylor 1972). At the upper elevational limits of its distribution and under stressful conditions, T. heterophylla tends to resemble T. mertensiana, e.g., leaves are less strictly 2-ranked and stomatal bands on the abaxial leaf surfaces are less conspicuous than at lower elevations.
Western hemlock (Tsuga heterophylla) is the state tree of Washington.
(Discussion copyrighted by Flora of North America; reprinted with permission.)
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