Thuja plicata



''Thuja plicata'' is an
evergreen In botany, an evergreen is a plant which has foliage that remains green and functional through more than one growing season. This also pertains to plants that retain their foliage only in warm climates, and contrasts with deciduous In the ...
conifer Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single extant class, Pinopsida. All e ...
tree In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, including only woody plants with secondary growth, plants that a ...
in the cypress
family Family (from la, familia) is a group of people related either by consanguinity Consanguinity ("blood relation", from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European ...
Cupressaceae, native to western North America. Its common name is western redcedar (western red cedar in the UK), and it is also called Pacific redcedar, giant arborvitae, western arborvitae, just cedar, giant cedar, or shinglewood. It is not a true cedar of the genus '' Cedrus''.


''Thuja plicata'' is a large to very large tree, ranging up to tall and in trunk diameter. Trees growing in the open may have a crown that reaches the ground, whereas trees densely spaced together will exhibit a crown only at the top, where light can reach the leaves. The trunk swells at the base and has shallow roots. The bark is thin, gray-brown and fissured into vertical bands. As the tree ages, the top is damaged by wind and replaced by inferior branches. The species is long-lived; some trees can live well over a thousand years, with the oldest verified aged 1,460. The foliage forms flat sprays with scale-like leaves in opposite pairs, with successive pairs at 90 degrees to each other. The foliage sprays are green above and green marked with whitish
stoma In botany, a stoma (from Greek ''στόμα'', "mouth", plural "stomata"), also called a stomate (plural "stomates"), is a pore found in the epidermis of leaves, stems, and other organs, that controls the rate of gas exchange. The pore is ...
tal bands below; they are strongly aromatic, with a scent reminiscent of pineapple when crushed. The individual leaves are long and broad on most foliage sprays, but up to long on strong-growing lead shoots. The foliage of individual branchlets turns orange-brown before falling off in autumn. The cones are slender, long, and broad, with 8 to 12 (rarely 14) thin, overlapping scales. They are green to yellow-green, ripening brown in fall about six months after pollination, and open at maturity to shed the seeds. The seeds are long and broad, with a narrow papery wing down each side. The
pollen Pollen is a powdery substance produced by seed plants. It consists of pollen grains (highly reduced microgametophytes), which produce male gametes (sperm cells). Pollen grains have a hard coat made of sporopollenin that protects the gameto ...
cones are long, red or purple at first, and shed yellow pollen in spring.


The heartwood of western redcedar contains numerous chemical substances, such as plicatic acid, thujaplicatin methyl ether, hinokitiol and other thujaplicins, β-thujaplicinol, thujic acid, methyl thujate, 1,4-cineole and γ-eudesmol. Plicatic acid is believed to be the main irritant and contact allergen responsible for provoking allergic reactions and
asthma Asthma is a long-term inflammatory disease of the airways of the lungs The lungs are the primary organs of the respiratory system in human Humans (''Homo sapiens'') are the most abundant and widespread species of primate, ...
exaggeration and leading to occupational asthma in woodworkers that are exposed to western redcedar wood dust. Thujaplicins serve as natural fungicides, and thereby prevent the wood from rotting. This effect lasts around a century even after the tree is felled. However, thujaplicins are only found in older trees. Saplings do not produce the chemical, causing them to often develop rot at an early stage, causing some trees to grow with a somewhat hollow trunk, as the tree moves to heal itself as it grows. Due to their fungicidal and anti- browning properties, thujaplicins are used in agriculture for fungal diseases and to prevent post-harvest decay. Thujaplicins, as other tropolones, are potent chelating agents and bind divalent metal ions.
Basic BASIC (Beginners' All-purpose Symbolic Instruction Code) is a family of general-purpose, high-level programming languages designed for ease of use. The original version was created by John G. Kemeny and Thomas E. Kurtz at Dartmouth Colleg ...
and animal studies have shown that thujaplicins may have other biological properties, including antibacterial, antiviral and antioxidant activities, however reliable evidence on their effectiveness is still lacking. Thuja bark Łazienki.JPG, The bark is fibrous and longitudinally fissured. Thuja plicata kz3.JPG, The leaves have white markings on the undersides of the flat foliage sprays. Thuja plicata 21 4 2017 Kaisaniemi 0016 (cropped).jpg, A shoot with pollen cones. Thuja plicata 43569.JPG, A shoot with mature seed cones, Mount Baker-Snoqualmie National Forest Western red cedars, looking up.jpg, Western redcedars on Keats Island, British Columbia Thuja_plicata_mutant_akin_gingko_on_two_trees_in_city_park,_Grenoble,_France.jpg, Mutation on t.plicata city park tree in Grenoble, France

Taxonomy and name

''Thuja plicata'' is one of two ''Thuja'' species native to North America, the other being '' Thuja occidentalis''. The species name ''plicata'' derives from the Latin word and means 'folded in plaits' or 'braided,' a reference to the pattern of its small leaves. Most authorities, both in Canada and the United States transliterate the English name in two words as 'western redcedar', or occasionally hyphenated as 'western red-cedar', to indicate that it is not a true cedar ('' Cedrus''), but it also appears as 'western red cedar' in some popular works. In the American horticultural trade, it is also known as the giant arborvitae, by comparison with arborvitae for its close relative ''Thuja occidentalis''. Other names include giant redcedar, Pacific redcedar, shinglewood,
British Columbia British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocea ...
cedar (being the province's official tree), canoe cedar, and red cedar. ''Arborvitae'' comes from the
Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through ...
for 'tree of life'; coincidentally, Native Americans of the West Coast also address the species as "long life maker". One endonymous name for the tree is the Halkomelem word , from the roots , meaning 'scratch' or 'line', and , 'bark'; the former root may be in reference to both the lined or "folded/braided" appearance of the bark and the tree's ubiquity in carving and other forms of woodwork.

Distribution and habitat

''Thuja plicata'' is among the most widespread trees in the Pacific Northwest. It is associated with Douglas-fir and western hemlock in most places where it grows. It is found in moist areas, where precipitation exceeds annually, west of the
Cascade Range The Cascade Range or Cascades is a major mountain range A mountain range or hill range is a series of mountain A mountain is an elevated portion of the Earth's crust Earth's crust is Earth's thin outer shell of rock, referring to ...
crest from central South East Alaska (near the village of Kake) to northern California (growing closer to the coast at the north and south extremes)and inland from central-southeast British Columbia through the Idaho Panhandle. It is usually found from
sea level Mean sea level (MSL, often shortened to sea level) is an average surface level of one or more among Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of wate ...
to elevations of , but grows at altitudes of up to at Crater Lake in
Oregon Oregon () is a state in the Pacific Northwest region of the Western United States. The Columbia River delineates much of Oregon's northern boundary with Washington, while the Snake River delineates much of its eastern boundary with Id ...
and in Idaho. In addition to growing in lush forests and mountainsides, western redcedar is also a riparian tree, growing in many forested swamps and streambanks in its range. The tree is shade tolerant and able to reproduce under dense shade. It has been introduced to other temperate zones, including further north in Alaska, western
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(at least as far north as
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, the eastern United States (at least as far north as Central New York), and higher elevations of
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. The species is naturalized in Britain.


Use by wildlife

Western redcedar foliage, especially that of saplings, is an important food source year-round for browsing
ungulate Ungulates ( ) are members of the diverse clade A clade (), also known as a monophyletic group or natural group, is a group of organisms that are monophyletic – that is, composed of a common ancestor and all its lineal descendants – ...
s such as Roosevelt elk and black-tailed deer, especially during the winter months when little else is available. The seeds are eaten by birds and rodents. Western redcedar provides cover for bears, raccoons, skunks, and other animals which nest inside trunk cavities. It is used as a nest tree by cavity-nesting bird species such as yellow-bellied sapsuckers, hairy woodpeckers, tree swallows, chestnut-backed chickadees, and Vaux's swifts. ''Thuja plicata'' is a host to several destructive insect species such as the western cedar borer, cedar bark beetle, gall midge, and conifer seedling weevils.

Forest succession

Western redcedar appears in all stages of forest succession, but as it is one of the most shade-tolerant species in the Rocky Mountains and Pacific Northwest it is considered to be a climax species along with western hemlock. It will readily establish and grow in the shade of other, less shade-tolerant species such as red alder, black cottonwood, or Douglas-fir, and prevent seedlings of those species from establishing themselves in its shade. However, western hemlock and Pacific silver fir are more tolerant of shade. Western redcedar can also reproduce vegetatively via layering.

Fire ecology

It is considered to have low to moderate fire resistance, as its thin bark, shallow roots, low dense branching
habit A habit (or wont as a humorous and formal term) is a routine of behavior that is repeated regularly and tends to occur subconsciously.
and flammable foliage confer little protection. Smaller trees are commonly killed by fire, but larger specimens often survive due to their size if they are not completely girdled. The intervals between fires within western redcedar stands tend to be very long, from 50 up to 350 years or more.


Western redcedar shows susceptibility of varying degrees to the following soil pathogens: '' Armillaria ostoyae, Fomitopsis pinicola, Heterobasidion annosum, Phaeolus schweinitzii, Phellinus weirii, Rhizinia undulata,'' and ''Postia sericeomollis.'' While western redcedar is a host to ''P. weirii,'' the fungus which causes the disease laminated root rot, redcedar is rated as resistant while other conifers are rated as highly susceptible or susceptible. Instead of laminated root rot, ''P. weirii'' in western redcedar expresses as a butt rot that can extend 2–3 m up the boles of living trees with the most extreme cases reaching 10 m. While the heart rot caused by the redcedar form of ''P. weirii'' does not kill the tree outright, it does severely weaken the lower portion of the bole which makes the tree highly susceptible to stem breakage. ''P. sericeomollis'' is responsible for brown cubical butt and pocket rot of cedar. It is the second-most common cause of decay in western redcedar following ''P. weirii''. Rather than forming a single column of decay in the heartwood, though, ''P. sericeomollis'' tends to cause rings or pockets of decay in the lower bole. In addition to ''P. weirii,'' western redcedar is also less susceptible to ''H. annosum'' and ''A. ostoyae'' than other conifer species. Studies have found that western redcedar produces a phytochemical called thujaplicin which has been credited with granting the species its natural resistance to fungal attacks. Because of these natural defenses, it has been suggested that western redcedar may serve as a suitable alternative to other conifers when regenerating a site affected by these pathogens.


Like its relative ''Thuja occidentalis'' and many other conifer species, ''Thuja plicata'' is grown as an ornamental tree, and for screens and hedges, throughout the world in
garden A garden is a planned space, usually outdoors, set aside for the cultivation, display, and enjoyment of plants and other forms of nature. The single feature identifying even the wildest wild garden A wildlife garden (or wild garden) is an e ...
s and parks. A wide variety of forms, sizes, and colours is available. ;Cultivars The following cultivars have gained the Royal Horticultural Society's Award of Garden Merit: *'Atrovirens' *'Aurea' *'Stoneham Gold' *'Whipcord' *'Zebrina'


In indigenous societies

Western redcedar has an extensive history of use by Native Americans of coastal Oregon to southeast Alaska. Some northwest coast tribes refer to themselves as "people of the redcedar" because of their extensive dependence on the tree for basic materials. The wood has been used for constructing housing and totem poles, and crafted into many objects, including masks, utensils, boxes, boards, instruments, canoes, vessels, houses, and ceremonial objects. Western redcedar is also associated with a long tradition of curing and cooking fish over the open fire. Roots and bark are used for baskets, bowls, ropes, clothing, blankets, and rings. A huge number of archaeological finds point to the continuous use of redcedar wood in native societies. Woodworking tools dating between 8,000 and 5,000 years ago, such as carved antlers, were discovered in shell middens at the Glenrose site, near
Vancouver Vancouver ( ) is a major city in western Canada, located in the Lower Mainland region of British Columbia. As the most populous city in the province, the 2021 Canadian census recorded 662,248 people in the city, up from 631,486 in 2016. ...
, British Columbia. In Yuquot, on the west coast of Vancouver Island, tools dating 4,000 to 3,000 years old have been found. The Musqueam site, also near Vancouver, yielded bark baskets woven in five different styles, along with ropes and ships dated to 3,000 years ago. At Pitt River,
adze An adze (; alternative spelling: adz) is an ancient and versatile cutting tool similar to an axe but with the cutting edge perpendicular to the handle rather than parallel. Adzes have been used since the Stone Age The Stone Age was a ...
s and baskets were dated around 2,900 years ago. Wooden artifacts 1000 years old were unearthed on the east coast of Vancouver Island. Red cedar was used extensively wherever it was found along the northwest coast (British Columbia, Washington state, parts of Alaska). Evidence of this use is found in CMTs ( Culturally Modified Trees) that are found throughout the coast. When First Nations people removed the bark from cedars, it left a scarwhich is considered a CMT. Other types of harvest (for planks, tinder, and other uses) leave different types of evidence of cultural modification. A legend amongst the Coast Salish peoples describes the origins of the western redcedar. In this legend, there was a generous man who gave the people whatever they needed. When the Great Spirit saw this, he declared that when the generous man died, a great redcedar tree will grow where he is buried, and that the cedar will be useful to all the people, providing its roots for baskets, bark for clothing, and wood for shelter.


The wood was worked primarily with the
adze An adze (; alternative spelling: adz) is an ancient and versatile cutting tool similar to an axe but with the cutting edge perpendicular to the handle rather than parallel. Adzes have been used since the Stone Age The Stone Age was a ...
, which was preferred over all other tools, even ones introduced by Europeans. Alexander Walker, an ensign on the fur trade ship ''Captain Cook'', reported that the indigenous peoples used an elbow adze, which they valued over tools brought by the Europeans, such as the saw or the axe, going so far as to modify traded tools back into an adze. Tools were generally made from stone, bone,
obsidian Obsidian () is a naturally occurring volcanic glass formed when lava extruded from a volcano cools rapidly with minimal crystal growth. It is an igneous rock. Obsidian is produced from felsic lava, rich in the lighter elements such as s ...
, or a harder wood such as hemlock. A variety of hand mauls, wedges, chisels, and knives are also used. Excavations done at Ozette, Washington, turned up iron tools nearly 800 years old, far before European contact. When
James Cook James Cook (7 November 1728 Old Style date: 27 October – 14 February 1779) was a British explorer, navigator A navigator is the person on board a ship or aircraft responsible for its navigation.Grierson, MikeAviation History—Demis ...
passed the area, he observed that almost all tools were made of iron. There has been speculation on the origin of these iron tools. Some theories include shipwrecks from
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or possible contact with iron-using cultures from
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, as hinted in the more advanced woodworking found in northern tribes such as the Tlingit.


Harvesting redcedars required some ceremony and included propitiation of the tree's spirits as well as those of the surrounding trees. In particular, many people specifically requested the tree and its brethren not to fall or drop heavy branches on the harvester, a situation which is mentioned in a number of different stories of people who were not sufficiently careful. Some professional loggers of Native American descent have mentioned that they offer quiet or silent propitiations to trees which they fell, following in this tradition. Felling of large trees such as redcedar before the introduction of steel tools was a complex and time-consuming art. Typically the bark was removed around the base of the tree above the buttresses. Then some amount of cutting and splitting with stone adzes and mauls would be done, creating a wide triangular cut. The area above and below the cut would be covered with a mixture of wet moss and clay as a firebreak. Then the cut would be packed with tinder and small kindling and slowly burned. The process of cutting and burning would alternate until the tree was mostly penetrated through, and then careful tending of the fire would fell the tree in the best direction for handling. This process could take many days. Constant rotation of workers was involved to keep the fires burning through night and day, often in a remote and forbidding location. Once the tree was felled, the work had only just begun, as it then had to be stripped and dragged down to shore. If the tree was to become canoes, then it would often be divided into sections and worked into rough canoe shapes before transport. If it were to be used for a totem pole or building materials, it would be towed in the round to the village. Many trees are still felled in this traditional manner for use as totem poles and canoes, particularly by artists who feel that using modern tools is detrimental to the traditional spirit of the art. Non-traditionalists simply buy redcedar logs or lumber at mills or lumber yards, a practice that is commonly followed by most working in smaller sizes such as for masks and staves. Because felling required such an extraordinary amount of work, if only planks for housing were needed, these would be split from the living tree. The bark was stripped and saved, and two cuts were made at the ends of the planking. Then wedges would be pounded in along the sides and the planks slowly split off the side of the tree. Trees which have been so harvested are still visible in some places in the rainforest, with obvious chunks taken off of their sides. Such trees usually continue to grow perfectly well, since redcedar wood is resistant to decay. Planks are straightened by a variety of methods, including weighing them down with stones, lashing them together with rope, or forcing them between a line of stakes. Redcedar wood is used to make huge monoxyla canoes in which the men went out to high sea to harpoon
whale Whales are a widely distributed and diverse group of fully Aquatic ecosystem, aquatic placental mammal, placental marine mammals. As an informal and Colloquialism, colloquial grouping, they correspond to large members of the infraorder Ce ...
s and conduct trade. One of those canoes, a craft dug out about a century ago, was bought in 1901 by Captain John Voss, an adventurer. He gave her the name of Tilikum ('Relative' in Chinook jargon), rigged her, and led her in a hectic three-year voyage from British Columbia to
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. Redcedar branches are very flexible and have good tensile strength. They were stripped and used as strong cords for fishing line, nets, rope cores, twine, and other purposes where bark cord was not strong enough or might fray. Both the branches and bark rope have been replaced by modern fiber and nylon cordage among the aboriginal northwest coast peoples, though the bark is still in use for the other purposes mentioned above.


At the right time of year, the bark is easily removed from live trees in long strips. It is harvested for use in making mats,
rope A rope is a group of yarns, plies, fibres, or strands that are twisted or braided together into a larger and stronger form. Ropes have tensile strength and so can be used for dragging and lifting. Rope is thicker and stronger than similar ...
and cordage, basketry, rain hats, clothing, and other soft goods. The harvesting of bark must be done with care, as stripping too much bark will kill the tree. To prevent this, the harvester usually only harvests from trees which have not been stripped before. After harvesting, the tree is not used for bark again, although it may later be felled for wood. Stripping bark is usually started with a series of cuts at the base of the tree above any buttresses, after which the bark is peeled upwards. To remove bark high up, a pair of platforms strung on rope around the tree are used and the harvester climbs by alternating between them for support. Since redcedars lose their lower branches as all tall trees do in the rainforest, the harvester may climb or more into the tree by this method. The harvested bark is folded and carried in backpacks. It can be stored for quite some time as mold does not grow on it, and is moistened before unfolding and working. It is then split lengthwise into the required width and woven or twisted into shape. Bark harvesting was mostly done by women, despite the danger of climbing ten meters in the air, because they were the primary makers of bark goods. Today bark rope making is a lost art in many communities, although it is still practiced for decoration or art in a few places. Other uses of bark are still common for artistic or practical purposes. In recent years there has been a revival of cedar weaving in some communities, and along with it, new forms of cedar bark products. For example, in some recent weddings cedar roses are used to decorate the tables.


The soft red-brown timber has a tight, straight grain and few knots. It is valued for its distinct appearance, aroma, and its high natural resistance to decay, being extensively used for outdoor construction in the form of posts, decking, shingles, and siding. It is commonly used for the framing and longwood in lightweight sail boats and kayaks. In larger boats it is often used in sandwich construction between two layers of epoxy resin and/or fibreglass or similar products. Due to its light weight driedit is about 30% lighter than common boat building woods, such as mahogany. For its weight it is quite strong but can be brittle. It glues well with epoxy resin or resorcinol adhesive. Its light weight, strength, and dark, warm sound make it a popular choice for
guitar The guitar is a fretted musical instrument A musical instrument is a device created or adapted to make musical sounds. In principle, any object that produces sound can be considered a musical instrument—it is through purpose that the obj ...
soundboards, particularly among European guitar builders such as Lowden and Furch. Western redcedar wood is export-restricted in the United States. The tree is highly allergenic and woodworkers or loggers who work with it may have adverse reactions, including the development of occupational asthma, exacerbation of existing
asthma Asthma is a long-term inflammatory disease of the airways of the lungs The lungs are the primary organs of the respiratory system in human Humans (''Homo sapiens'') are the most abundant and widespread species of primate, ...
, reduction of lung function, and eye irritation. Approximately 5% of workers are allergic to western redcedar. The US Occupational Safety and Health Administration has set a permissible exposure limit for red cedar dust of 2.5 mg/m3 as a time-weighted average over eight hours.

Essential oil

The essential oil of western redcedar leaves contains natural compounds, such as α- thujone, β- thujone, fenchone, sabinene, terpinen-4-ol and beyerene, which have also been isolated from different other essential oils. Some of these substances are aroma compounds and are used in perfumery. Thujones are GABAA receptor competitive antagonists however because of their high toxicity and convulsive activity they do not have any pharmacological use.

Other uses

It is also widely used throughout Europe and America for making beehive components. Its bark has been studied for applications in polyurethane. Used in the construction of windows and doors (joinery grade timber).

Notable specimens

The largest living specimen is the Cheewhat Giant, in Pacific Rim National Park Reserve on Vancouver Island, at . The tallest known individual is the Willaby Creek Tree south of Lake Quinault, in height. The 'Quinault Lake Redcedar' was the largest known western redcedar in the world, with a wood volume of . Located near the northwest shore of Lake Quinault north of Aberdeen, Washington, about from the Pacific Ocean, it was one-third the volume of the largest known tree, a giant sequoia named ' General Sherman'. The Quinault Lake Redcedar was tall with a diameter of at breast height. The Quinault Lake Redcedar was destroyed by a series of storms in 2014 and 2016 and is now only a glorified stump. The fifth-largest known was the Kalaloch Cedar in Olympic National Park, at , until it was destroyed by a storm in March 2014. A redcedar over tall, in diameter, and over 700 years old stood in Cathedral Grove on Vancouver Island before it was set on fire and destroyed by vandals in 1972. That tree now lies in "Giant's Grave", a self-dug 'grave' created by the force of its own impact.Picture of the Cathedral Grove stump.
/ref> A specimen measuring diameter and tall on the Giant Red Cedar National Recreation Trail in the Idaho Panhandle National Forests is designated the "Champion Tree of Idaho". The Giant Cedar Stump is an ancient redcedar turned roadside attraction in Snohomish County, Washington.

See also

* Cedar wood * List of superlative trees


Works cited

* * * * * * * * * * * * * *

External links

* * * * {{Authority control plicata Trees of the West Coast of the United States Trees of Western Canada Trees of the Northwestern United States Trees of Alaska Trees of British Columbia Trees of the Southwestern United States Flora of the Cascade Range Flora of the Klamath Mountains Flora of the Rocky Mountains Flora of California Trees of mild maritime climate Trees of Subarctic America Plants described in 1824 Building materials Provincial symbols of British Columbia Least concern plants Least concern flora of North America Least concern flora of the United States