Pacific Hemlock Tsuga heterophylla
Other Common Name(s):
- Phonetic Spelling
- SU-ga het-er-oh-FIL-uh
- Description
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Western hemlock is a large, needled evergreen coniferous tree that is the state tree of Washington. A mature tree can reach a height of 150 feet to 195 feet and a width of 30 feet or more. The trunk of the tree has been known to reach up to 9 feet in diameter. It has a broad, erect, pyramidal habit, and narrow conical crown. The tree has variable needle lengths that are dark green to blue grayish-green, and it produces abundant small brown seed cones. The western hemlock is a member of the Pinaceae or pine family.
It is native to southern Alaska and down to the west coast of California. They are also found in the Rocky Mountains of southeastern British Columbia, northern Idaho, and southwestern Montana. This tree prefers coastal and mid-mountain forests. Reportedly, the tallest western hemlock is over 240 feet tall, and some of the trees are over 1200 years old.
The genus name, Tsuga, originated from the Japanese word that means "mother" and "tree." The species name, heterophylla, is Greek for "variable leaves" which refers to the variable length of the western hemlock needles.
Western hemlock prefers full sun but is tolerant of partial shade to full shade. It grows well in acidic soils and needs moist to wet soils with good drainage. The tree has a shallow root system and can be prone to wind damage and is intolerant to drought. Seedlings typically grow on decaying wood and grow slowly in shade. In the presence of the full sun, they grow much faster. The western hemlock may also germinate on the surface of the soil and requires cold stratification. Propagation by layering and cuttings has also been reported.
The western hemlock is a favorite habitat for many birds. The seeds from the cones are a food source for Chickadees, Pine Siskins, and Deer Mice. Some small mammals nibble on the bark, and deer and elk browse and enjoy the foliage.
The western hemlock may be confused with the eastern hemlock (Tsuga canadensis). The distinction is made by comparing the needles' size and arrangement, the size of the bands on the undersides of the needles, and the shape of the buds.
Quick ID Hints:
- bark is grayish-brown, scaly, and fissured
- foliage is finely textured and fern-like and droops at the ends
- flat needles, spirally arranged with different sizes alternating on the same stem
- lower surface of the needle has two white broad bands and unclear green margins
- buds are spherical
- small woody cones appear in August
Pests, Diseases, and Other Plant Problems: Hemlock wooly adelgids may be found on the foliage and suck the sap from the tree. They appear as small white nodes on the underside of the branches. Defoliating insects such as the larvae from caterpillars may kill the tree if the damage is severe. These insects include hemlock looper larvae, silver-spotted tiger moth larvae, and hemlock sawfly larvae. Parasites such as hemlock dwarf mistletoe can rob the tree of nutrients. Bracket fungi or conks cause the wood to decay. Porcupines are known to gnaw on the bark. Due to the shallow root system, wind damage and drought can be problematic.
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:
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- 'Thorsen's Weeping'
- 'Thorsen's Weeping'
- 'Thorsen's Weeping'
- Tags:
- Cultivars / Varieties:
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- 'Thorsen's Weeping'
- 'Thorsen's Weeping'
- 'Thorsen's Weeping'
- Tags:
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Attributes:
- Genus:
- Tsuga
- Species:
- heterophylla
- Family:
- Pinaceae
- Uses (Ethnobotany):
- Western hemlock is primarily used for making lumber for building. It is the best source of pulpwood for use in paper production and is also used to make cellophane. American Natives used the timber for firewood or making poles. They also used the bark to make dye or paint, and they used the pitch as a cosmetic. Western hemlock has been used in bonsai.
- Life Cycle:
- Woody
- Recommended Propagation Strategy:
- Layering
- Seed
- Stem Cutting
- Country Or Region Of Origin:
- Southern Alaska to Northern California
- Distribution:
- Native: Canada--British Columbia; US--AK, CA, ID, MT, OR, and WA. Introduced: Denmark, France, Germany, Great Britain, Ireland, and Norway.
- Wildlife Value:
- Western hemlock is a nesting site for birds. Deer, mice, and birds eat the seeds from the cones. Small mammals eat the bark. Deer and elk browse on the foliage and stems.
- Play Value:
- Wildlife Cover/Habitat
- Wildlife Food Source
- Wildlife Nesting
- Dimensions:
- Height: 60 ft. 0 in. - 240 ft. 0 in.
- Width: 12 ft. 0 in. - 40 ft. 0 in.
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Whole Plant Traits:
- Plant Type:
- Tree
- Woody Plant Leaf Characteristics:
- Needled Evergreen
- Habit/Form:
- Broad
- Conical
- Erect
- Pyramidal
- Growth Rate:
- Medium
- Maintenance:
- Low
- Texture:
- Fine
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Cultural Conditions:
- Light:
- Deep shade (Less than 2 hours to no direct sunlight)
- 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:
- High Organic Matter
- Soil pH:
- Acid (<6.0)
- Soil Drainage:
- Good Drainage
- Moist
- Occasionally Wet
- Available Space To Plant:
- more than 60 feet
- USDA Plant Hardiness Zone:
- 5a, 5b, 6a, 6b, 7a, 7b, 8a, 8b
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Fruit:
- Fruit Color:
- Brown/Copper
- Gold/Yellow
- Purple/Lavender
- Display/Harvest Time:
- Fall
- Fruit Length:
- < 1 inch
- Fruit Width:
- < 1 inch
- Fruit Description:
- The male cones are tiny and yellow and grow axillary on last year's growth. The female cones are tiny and purple and appear on the distal ends of the twig. The male and female cones first appear in the spring. As they mature, the cone is a small light brown elliptical or egg-shaped seed cone and has ovate scales. The cones measure 0.6 to 1 inch long and 0.6 to 1 inch wide and appear terminally on the twigs. The apex of the cone may be rounded or pointed. A cone contains 30 to 40 seeds. Each seed measures about 2-3 mm in length. The cones mature in August, and the seeds ripen by late September. By October, the cones will open to release the seeds.
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Leaves:
- Woody Plant Leaf Characteristics:
- Needled Evergreen
- Leaf Color:
- Blue
- Gray/Silver
- Green
- Leaf Feel:
- Soft
- Leaf Type:
- Needles
- Leaf Arrangement:
- Alternate
- Leaf Shape:
- Acicular
- Linear
- Leaf Margin:
- Dentate
- Hairs Present:
- No
- Leaf Length:
- < 1 inch
- Leaf Width:
- < 1 inch
- Leaf Description:
- The leaves are single soft flat needles that are arranged in spirals. They have varying lengths that alternate on the twig which are distinctive of this species. They measure 0.25 to 0.75 inches long with rounded tips. The needles on new growth appear bright green and become dark green as they mature. The surface below is grayish-green or blue and has two white bands. The margins of the needles are finely dentate.
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Bark:
- Bark Color:
- Black
- Light Brown
- Light Gray
- Surface/Attachment:
- Fissured
- Ridges
- Scaly
- Bark Description:
- The bark on a young tree is thin, brown to black, and the upper layer is scaly. On older trees, the bark is grayish-brown, thin, fissured, and has flat ridges. The interior bark is red and has streaks of purple.
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Stem:
- Stem Color:
- Brown/Copper
- Gold/Yellow
- Stem Is Aromatic:
- No
- Stem Leaf Scar Shape:
- Round
- Stem Surface:
- Hairy (pubescent)
- Stem Description:
- The twigs or stems are yellowish-brown, slender, and flexible. They have fine hairs, and the leaf scars are rounded. The buds are spherical, grayish brown, and measure 2.5 to 3.5 mm.
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Landscape:
- Landscape Location:
- Woodland
- Design Feature:
- Screen/Privacy
- Specimen
