Mountain hemlock

Silhouette - mountain hemlock
  • Latin name: Tsuga mertensiana (Bong.) Carrière
  • French name: Pruche subalpine
  • Synonym(s): Black hemlock
  • Taxonomic Serial Number: 183402
Description

Leaves

  • Twig and needles - mountain hemlock
  • Twig terminal with needle (above); needle cross section (below) - mountain hemlock

Form

  • Rounded in cross-section, blunt-tipped
  • Needles crowded, spreading around the twig, especially on upper side

Length

  • 20–30 mm

Colour

  • Both surfaces dark bluish-green with faint lines of white dots

Buds

Form

  • Ovoid
  • Outer scales with narrow, pointed tips

Length

  • 5 mm

Colour

  • Reddish-brown

Twigs

Form

  • Slender to stoutish, hairy
  • Side branches of unequal length, forming a tufted spray

Colour

  • Reddish-brown

Seed cones (mature)

  • Seed cones, closed (left) and open (right) - mountain hemlock
  • Cone scales; outer surface with bract (left), inner surface and winged seed (center), winged seed and seed (right) - mountain hemlock

Form

  • Oblong cylindrical

Length

  • 30–80 mm

Colour

  • Purplish-brown

Structure

  • Scales thickened, broad, fan-shaped
  • Margins slightly roughened or toothed

Timing

  • Open in autumn, spreading very widely
  • During winter becoming bent back toward the cone base after the seeds have been shed
  • Cones fall off during the spring or early summer

Seedlings

Form

  • Seeds germinate in spring, even on snow

Bark

Form

  • Scaly
  • Divided into hard, narrow, flat-topped ridges

Colour

  • Dark reddish-brown

Wood

Texture

  • Moderately light
  • Relatively hard and strong

Colour

  • Heartwood light reddish-brown

Morphology

  • Heartwood not sharply distinct from the sapwood
  • Fine-grained

Size

Height

  • Usually to 15 m, occasionally 45 m on exceptional sites

Diameter

  • To 50 cm

Maximum age

  • Several hundred years old

Tree form

  • Silhouette - mountain hemlock

Forest-grown

Trunk

  • At lower elevations, trunk strongly tapered, bearing slender branches with upturned tips, almost to the ground

Crown

  • Narrowly conical, becoming irregular and bent or twisted on old trees
  • Leading shoot oblique

Root system

  • Shallow, wide-spreading

Habitat

Site

  • Coastal and interior subalpine forests
  • Grows best on deep moist soils on north slopes
  • In wetter areas of the subalpine forest at elevations of 750–1800 m
  • On exposed ridges at high elevations, a low-spreading shrub

Light tolerance

  • Seedlings grow best in partial shade

Associated species

  • In pure stands or mixed with subalpine fir, amabilis fir, Engelmann spruce, subalpine larch, whitebark pine, and lodgepole pine

Range

Coastal and interior northern British Columbia and Alaska

Insects and diseases

Insects and diseases that are found most frequently and/or that cause the most damage in our Canadian forests.

Photos
  • Mountain hemlock
  • Mountain hemlock
Distribution map
Distribution map - mountain hemlock
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