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Tsuga mertensiana is often confused with:
Tsuga canadensis Form
Tsuga caroliniana Tsuga caroliniana
Tsuga heterophylla
Native alternative(s) for Tsuga mertensiana:
Tsuga caroliniana Tsuga caroliniana
Plants that fill a similar niche:
Thuja occidentalis 'Degroot's Spire'
Taxus baccata
Tsuga heterophylla
Tsuga mertensiana has some common insect problems:
Hemlock Woolly Adelgid

Tsuga mertensiana

Previously known as:

  • Abies mertensiana
  • Hesperopeuce mertensiana
Phonetic Spelling
SU-ga mer-TEN-si-a-na
Description

Mountain hemlock is a medium-sized needled, coniferous, evergreen tree that has a narrow width but can mature to heights of 30 to 100 feet. It has a conical or pyramidal crown, dense foliage, spreading branches, and the leading shoot may be tilted. The bark is grayish-black to reddish-brown and is fissured and scaly. The greenish-blue to silver-green needles are the same lengths and dense on all sides with a bottle brush effect. The seed cones are purple and then ripen to a grayish-brown. Mountain hemlock is a member of the Pinaceae or pine family.

The mountain hemlock is native to the southeast coasts of Alaska and British Columbia. It is also native to the mountains of the States of Washington, Oregon, the high Sierras of California, and the high Sierras of Nevada. It can be found in parts of Idaho and Montana. It typically is found at higher altitudes in the United States. In subalpine areas, the tree may only reach a height of 10 feet; however, in lowlands, it may reach a height of 100 feet. The tallest known trees have reached 175 feet. and the oldest trees are 500 to 1400 years old.

The genus name, Tsuga, originated from the Japanese word "tsu-ga," which means "tree" and "mother." The species name, mertensiana,  is named in honor of a German botanist, Franz Karl Mertens.

The mountain hemlock prefers full sun and moist, cool summers. They do not perform well in the southeastern United States due to their intolerance to the heat. The tree may be propagated by seedlings, cuttings, and layering

The trunks of the tree are flexible and can withstand the weight of snow for months in alpine regions.  After the snow melts, the tilted trees will upright themselves. The mountain hemlock is less tolerant to shade than the western hemlock. Squirrels eat the seeds from the cones, and grouse like to forge on the buds and leaves.

This tree does best in areas where the growing season is short, and the winters are cold and long. When the mountain hemlock is young, it may be pruned as a hedge. 

Seasons of Interest:

Bark: Spring, Summer, Fall, and Winter   Foliage: Spring, Summer, Fall, and Winter    Fruits: Spring, Summer, and Fall

Quick ID Hints:

  • branches raise upward at the tips
  • needles are of equal length, dense on all sides of the stems in a bottle brush effect
  • cones are narrow and long, measuring about 3 inches long and 1 inch wide

Pests, Diseases, and Other Plant Problems:  The mountain hemlock has no serious disease or insect problems. Hemlock adelgid may be found on the foliage and will appear as white cotton tufts. Trees that are heavily infested will need to be removed.

VIDEO created by Ryan Contreras for “Landscape Plant Materials I:  Deciduous Hardwoods and Conifers or Landscape Plant Materials II:  Spring Flowering Trees and Shrubs” a plant identification course offered by the Department of Horticulture at Oregon State University

Profile Video:
See this plant in the following landscape:
Cultivars / Varieties:
  • 'Elizabeth'
    spreading dwarf
'Elizabeth'
Tags:
#specimen#slow growing#pyramidal#conifer#low maintenance#small mammals#needled evergreen#deer resistant#alpine#rock garden#acidic soils tolerant#screening#evergreen tree#bird friendly#partial shade tolerant#native#wildlife food source#container#full sun#landscape plant sleuths course
 
Cultivars / Varieties:
  • 'Elizabeth'
    spreading dwarf
'Elizabeth'
Tags:
#specimen#slow growing#pyramidal#conifer#low maintenance#small mammals#needled evergreen#deer resistant#alpine#rock garden#acidic soils tolerant#screening#evergreen tree#bird friendly#partial shade tolerant#native#wildlife food source#container#full sun#landscape plant sleuths course
  • Attributes:
    Genus:
    Tsuga
    Species:
    mertensiana
    Family:
    Pinaceae
    Uses (Ethnobotany):
    The mountain hemlock is used primarily as an ornamental. Its wood is inferior to the western hemlock and is not typically used for lumber or pulpwood. This tree grows in high altitudes which also makes it difficult to access. Native Americans of the Pacific Northwest tribes used the leaves to make a poultice to treat burns. They used the bark to treat colds, flu, and nausea. The bark was also used for coloring their skin and tanning hides.
    Life Cycle:
    Woody
    Recommended Propagation Strategy:
    Layering
    Seed
    Stem Cutting
    Country Or Region Of Origin:
    Alaska to Western U.S.A.
    Distribution:
    Native: Canada--British Columbia; U.S.--AK, CA, ID, MT, NV, OR, and WA.
    Wildlife Value:
    The seeds are eaten by birds and squirrels.
    Play Value:
    Wildlife Food Source
    Wind Break
    Dimensions:
    Height: 30 ft. 0 in. - 100 ft. 0 in.
    Width: 10 ft. 0 in. - 15 ft. 0 in.
  • Whole Plant Traits:
    Plant Type:
    Tree
    Woody Plant Leaf Characteristics:
    Needled Evergreen
    Habit/Form:
    Conical
    Pyramidal
    Growth Rate:
    Slow
    Maintenance:
    Low
    Texture:
    Fine
  • Cultural Conditions:
    Light:
    Full sun (6 or more hours of direct sunlight a day)
    Partial Shade (Direct sunlight only part of the day, 2-6 hours)
    Soil Texture:
    Clay
    High Organic Matter
    Loam (Silt)
    Sand
    Shallow Rocky
    Soil pH:
    Acid (<6.0)
    Soil Drainage:
    Good Drainage
    Moist
    USDA Plant Hardiness Zone:
    5b, 5a, 6b, 6a, 7b, 7a, 8b, 8a
  • Fruit:
    Fruit Color:
    Brown/Copper
    Red/Burgundy
    Display/Harvest Time:
    Fall
    Summer
    Fruit Length:
    1-3 inches
    Fruit Width:
    < 1 inch
    Fruit Description:
    The cones first appear in mid-May to mid-July. The male cones are bluish and less than 0.25 inches long. The female cones are cylinder-like, light to dark purple or brownish purple, and less than 3 inches long. The mature seed cones measure 1 to 3 inches long and 0.5 to 1.5 inches wide. They will ripen to a reddish-brown and have fan-shaped scales. The cones open from late September to November. The seeds are reddish-brown and about 2-3 mm long.
  • Leaves:
    Woody Plant Leaf Characteristics:
    Needled Evergreen
    Leaf Color:
    Blue
    Gray/Silver
    Green
    Leaf Type:
    Needles
    Leaf Shape:
    Acicular
    Linear
    Leaf Margin:
    Entire
    Hairs Present:
    No
    Leaf Length:
    < 1 inch
    Leaf Width:
    < 1 inch
    Leaf Description:
    The leaf is a needle-type and measures 0.5 to 0.75 inches long, and the needles cover the branch on all sides, similar to a bottle brush. The needles are grayish-green or bluish-green, and the margins are entire.
  • Bark:
    Bark Color:
    Black
    Dark Brown
    Red/Burgundy
    Surface/Attachment:
    Fissured
    Scaly
    Bark Description:
    The young bark is thin, scaly, and brown to black. The bark on mature trees is reddish-brown with deep fissures.
  • Stem:
    Stem Color:
    Brown/Copper
    Gold/Yellow
    Stem Is Aromatic:
    No
    Stem Leaf Scar Shape:
    Round
    Stem Surface:
    Hairy (pubescent)
    Stem Description:
    The stems are slender to stout, yellow orangish-brown, and maybe smooth or densely hairy. The buds are oblong and are 3-4 mm long.
  • Landscape:
    Landscape Location:
    Container
    Recreational Play Area
    Woodland
    Landscape Theme:
    Rock Garden
    Design Feature:
    Hedge
    Screen/Privacy
    Specimen
    Resistance To Challenges:
    Deer