Mountain hemlock
- Latin name: Tsuga mertensiana (Bong.) Carrière
- French name: Pruche subalpine
- Synonym(s): Black hemlock
- Taxonomic Serial Number: 183402
Description
Leaves
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)
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
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
Photos
Photos
Anthony Scullion
Insects and mites
Insects that cause damage to this tree.
-
Hemlock woolly adelgid
Scientific name: Adelges tsugae Annand
Cones or seeds
Foliage or buds
- Enypia venata (Grote)
- Eupithecia longipalpata (Packard)
- Gabriola dyari (Taylor)
-
Green velvet looper
Scientific name: Epirrita autumnata (Harrison)
-
Greenstriped forest looper
Scientific name: Melanolophia imitata (Walker)
-
Hemlock sawfly
Scientific name: Neodiprion tsugae Middleton
- Hydriomena irata Swett
- Hydriomena speciosata (Packard)
-
Larch pug moth
Scientific name: Eupithecia annulata (Hulst)
-
Packard’s gridle moth
Scientific name: Enypia packardata (Taylor)
-
Redlined conifer caterpillar
Scientific name: Feralia jocosa (Gn.)
-
Spruce fir looper
Scientific name: Macaria signaria dispuncta (Walker)
- Synaxis pallulata (Hulst)
- Thallophaga hyperborea (Hulst)
-
Western blackheaded budworm
Scientific name: Acleris gloverana (Walsingham)
-
Whitelined looper
Scientific name: Epirrita pulchraria (Taylor)
- Xestia mustelina (Smith)
-
Yellowlined forest looper
Scientific name: Cladara limitaria (Walker)
Roots, bark, stem or trunk, or branches
Diseases caused by pathogens
Diseases caused by pathogens that cause damage to this tree.
Black stain root disease
Pathogen name: Grosmannia wageneri (Goheen & F.W. Cobb) Zipfel, Z.W. Beer & M.J. Wingf.
-
Black stain root disease
Pathogen name: Grosmannia wageneri (Goheen & F.W. Cobb) Zipfel, Z.W. Beer & M.J. Wingf.
-
Brown cubical sap rot
Pathogen name: Gloeophyllum sepiarium (Wulfen: Fr.) P. Karst.
-
Fir-willow rust
Pathogen name: Melampsora abietis-capraearum Tub.
-
Ribes-willow rust
Pathogen name: Melampsora ribesii-purpureae
Cones or seeds
-
Brown felt blight
Pathogen name: Herpotrichia juniperi (Duby) Petr.
-
Sirococcus Shoot Blight
Pathogen name: Sirococcus conigenus (Dc.) Cannon & Minter
Foliage or buds
-
Brown felt blight
Pathogen name: Herpotrichia juniperi (Duby) Petr.
-
Hemlock - Blueberry rust
Pathogen name: Naohidemyces vaccinii (Wint.) Sato, Katsuya et Hiratsuka
-
Hemlock-willow rust
Pathogen name: Melampsora epitea Thuem.
-
Sirococcus Shoot Blight
Pathogen name: Sirococcus conigenus (Dc.) Cannon & Minter
Roots, bark, stem or trunk, or branches
Distribution map
