Tuesday, October 12, 2010

Tsuga heterophylla - Western Hemlock

Tsuga heterophylla: Tsuga is from a Japanese name for their native hemlocks; heterophylla, meaning 'different leaves' referring to the short and longer needles that grow together along a branchlet.

Tall, straight tree with a drooping leader and branch tips. Growth rate slow to moderate up to 150+' in its native habitat by 20-30' wide, developing a tall, pyramidal form. Often rather spindly and shapeless in its densely shaded forest habitat, becoming more shapely in sunnier locations.


Needles are glossy, yellow-green, 1/2" long, appearing to grow from opposite sides of branchlets. appearing 2-ranked, or in a flattened profile, from a short stem, with grooved uppersides, persisting 3-4 years.


Cones are light brown, elliptical, 1" long with thin papery scales, hanging along ends of branchlets, maturing in summer of the first season.


Bark is thin, brown, finely scaled, becoming thicker and harder, dark brown and red-tinged, deeply furrowed, with flat, wide ridges irregularly interconnected with narrow cross-ridges.


Evergreen. Native to the Pacific Coast from Alaska to northern California at 2,000-5,000' elevation. Western hemlock is mainly a tree of temperate rainforests, but it also occurs in the northern Rockies. On the coast it may experience 150" of rain (in Alaska), or less than 40" (Eureka, California). Inland it is confined to shady, north-facing slopes and stream bottoms. It tolerates a wide variety of soils and ranges from sea level to 2,000 feet. Grows mostly among Sequoia sempervirens, Picea sitchensis and Thuja plicata.

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