What is a Western Hemlock Tree? - Home Stratosphere

What is a Western Hemlock Tree?

Here is everything you need to know about the Western Hemlock tree, what it looks like, how it reproduces, where it usually grows and how the Western Hemlock tree is used.

This is a road surrounded by a forest of Western Hemlock trees.

Tsuga Heterophylla

The western hemlock tree, or sometimes the western hemlock spruce tree, is a tree that is native to the west coast of North America in very specific ranges. They are an integral member of the Pacific Northwest coastal forest ranges, where they are a very successful climax species.

Western hemlocks are the very largest of the hemlock species. Though they are a semi slow growing tree, they are incredibly long lived, with many members living to be over 1200 years old. The tallest known specimen of western hemlock is 82.83 meters, and it lives in the Prairie Creek Redwoods State Park in California. This tree is also the state tree of Washington.

If you’re feeling curious about trees, we’ve compiled an awesome list of 101 Types of Trees from around the world. You can learn about different hemlock tree species, fruit tree species, huge tree species, small tree species, and everything in between.

Table of Contents

Related: Mountain Hemlock Tree | Eastern Hemlock Tree | Types of Hemlock Trees

What do Western Hemlock Trees Look Like?

Root System

Hemlock trees, since they usually grow in rocky soils and regularly harsh climates, will develop two different types of root systems to help keep them both stable and well-fed. They will develop both a taproot and laterally spreading fibrous roots.

A taproot (which hemlock trees have in common with carrots, funnily enough) is one or several large roots that grow directly down into the earth. A hemlock tree will first develop this root system as a sapling grows. This helps keep the tree stable and allows it to access moisture reserves deep in the earth.

Once a healthy taproot is grown, fibrous roots will start to grow from the taproot. These roots are dense and wide-spreading. This helps keep the tree stable and upright against the sometimes harsh mountainous conditions that hemlocks usually grow in.

Dimensions

Western hemlocks are the largest hemlock tree species. These large trees can grow upwards of 50 to 70 meters in height, with an average trunk diameter of 2.7 meters. The most exceptionally large western hemlock is 82.32 meters tall!

large western hemlock tree growing in landscape with other conifers

Growth Pattern

Young trees have a very neat, conic, and broad crown. These tree crowns are known for having a drooping lead shoot, which is a key identifier of a hemlock tree. Another key identifier of hemlocks is their pendulous drooping branchlet tips.

A mature tree will have a more cylindrical crown shape, and it will have self pruned away the branches on the bottom half of the trunk.

Bark

Western hemlock bark is a dark brown color, peels away in thin sheets, and has distinguishable furrows throughout the bark.

Foliage

Western hemlock trees are an evergreen tree species, meaning that their foliage will both remain green all year long, and persist throughout the year. There are some tree species that can keep the same foliage for over 10 years!

Western hemlocks have needle like leaves. They are less than an inch long with a finely serrated margin, a blunt apex, and are slightly flattened in a cross section. This makes them soft to the touch, unlike pine trees that can be quite prickly.

The western hemlock needle is dark green on the upper surface with an underside that possesses distinct white bands of stomata. These needles are arranged spirally along their shoots, and grow in 2 ranks on either side.

young soft and green western hemlock tree needles growing on a stock

How do Western Hemlock Trees Reproduce?

Cones

Hemlock trees are monoecious, meaning that they possess both male cones (pollen cones) and female cones (seed cones). Though they are able to self pollinate, pollen will usually be dispersed to either a seed cone on the same tree, or a seed cone on a different tree.

Both seed cones and pollen cones are slender, have a cylindrical shape, and are pendulous on a branch. Cones are just over an inch long and have between 15 and 25 flexible scales. Immature cones are first green, and they eventually mature to a brown color about 5-7 months after their original pollination.

Seeds

Pollen cones will open their scales to release pollen. The pollen is wind dispersed and enters the open scales of seed cones. The pollen will fertilize the ovule inside the seed cone, where the scales with then close as the western hemlock seed grows.

Once the cone and seed is mature, the scales will open once more for the seeds to be released. Mature seeds are slender and brown, with a pale brown wing to help with dispersal.

Sexual Maturity

Western hemlocks will usually start to produce seed crops around 15 years of age, with their most productive crops occurring between the ages of 75 and 150. This may seem like a delayed reproductive start, but considering that these trees can usually live to be around 1200, it isn’t all that late!

mature western hemlock tree cones hanging from a branch

What are some Other Species of Hemlock?

The Mountain Hemlock Tree (Tsuga Mertensiana)

Mountain hemlock trees have a very similar native range to the western hemlock tree, though they grow at higher altitudes and on rocky mountain sites. They are a large tree, usually hovering around 20 40 meters in height but exceptionally reaching 60 meters. They look almost identical to the western hemlock and grow in snowy subalpine sites.

The Carolina Hemlock Tree (Tsuga Caroliniana)

Carolina hemlocks are native to the Appalachian mountains of southwestern Virginia. They can commonly be found growing on rocky mountain slopes at high altitudes, between 700 and 1200 meters in altitude. They grow to be an average of 30 meters in height, and exceptional trees can be over 34.

The Eastern Hemlock Tree (Tsuga Canadensis)

Eastern hemlocks are some of the smaller species of hemlock trees. They are sometimes referred to as eastern hemlock spruce trees and are native to the northeastern parts of the United States. They can be found growing in ridges and ravines that receive high annual precipitation. They grow to be an average of 25-30 meters tall.

view of the spring foliage of an eastern hemlock tree in the sunlight

Where do Western Hemlock Trees Grow?

A western hemlock tree will always grow within 62 miles of the Pacific coast. They are a coastal native plant, and are closely associated with temperate rainforests of the Pacific Northwest.

Western hemlocks grow at lower altitudes than mountain hemlock trees, usually from sea level up until 600 meters in altitude, whereas the mountain hemlock will grow in the northern rocky mountains. However, in the interior of Idaho they will grow up to 1800 meters in altitude.

Outside of their natural range, western hemlocks have been cultivated and naturalized in Great Britain, New Zealand, and many other temperate regions around the world.

western hemlocks and other conifers growing beside large river and foggy mountains

What are the Growing Conditions of Western Hemlock Trees?

Soil

Western hemlocks prefer to grow in moist mineral soil that is well drained. They perform extremely well in soil that has a high level of organic decaying matter.

Water Level

The western hemlock is a tree that is very closely associated with temperate rainforest climates. This means that they require very high levels of annual precipitation.

Sun Exposure

Slightly unusual for an evergreen conifer, the western hemlock tree is a very shade tolerant tree. They are known to exceed shade tolerance even by the western red cedar, Pacific yew and the Pacific silver fir.

A western hemlock seedling will often grow under the thick canopy of sitka spruce and Douglas fir trees. Here, they will wait, sometimes for decades, for the mature trees to die and for a spot in the coveted forest canopy to open up.

Thanks to this high level of patience, western hemlocks will often replace other conifers that are shade intolerant.

western hemlock trees growing in rain forest climate mossy logs damp earth

How are Western Hemlock Trees Used?

Wood

Western hemlock wood is softwood. It is a light cream color with a straight grain, and it is easily worked. Hemlock wood is very important in the lumber industry, timber industry, and paper pulp industry. This wood is also often used to create doors, furniture, and joinery as well.

Wildlife

Hemlock trees are known for having a tight knit symbiotic relationship with different fungi species, especially the chanterelle mushroom. This relationship is integral to the decay of organic plant matter on the forest floor.

The western hemlock is also used in forestry. They are planted along river banks to help reduce erosion, thanks to their woody and dense root systems.

Ornamental

Western hemlocks are popular ornamental trees in Europe, New Zealand, and in certain parts of North America as well. Thanks to their attractive needle color and interesting shape, they are used in gardens, parks, and as street trees.

Nutrition

Eating the inner bark of the western hemlock tree has been done by the First Nations folks of North America for centuries. The inner cambium layer is collected by scraping large slabs of bark. This can be eaten either raw, or pressed into bread!

It is also well known that young western hemlock needles are a great source of vitamin C. These can be eaten either raw or made into tea.

western hemlock trees growing beside stream to help with soil erosion

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