| Thuja occidentalis | |
|---|---|
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| Leaves and immature cones | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Gymnospermae |
| Division: | Pinophyta |
| Class: | Pinopsida |
| Order: | Cupressales |
| Family: | Cupressaceae |
| Genus: | Thuja |
| Species: | T. occidentalis |
| Binomial name | |
| Thuja occidentalis | |
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| Natural range | |
Thuja occidentalis, also known asnorthern white-cedar,[1]eastern white-cedar,[2] orarborvitae,[2][3] is anevergreenconiferoustree, in the cypress familyCupressaceae, which isnative to eastern Canada and much of the north-central and northeastern United States.[3][4] It is widely cultivated as an ornamental plant. It is not to be confused withJuniperus virginiana (eastern red cedar).
Its additional common names includeswamp cedar,[3]American arborvitae,[4] andeastern arborvitae.[4] The name arborvitae is particularly used in thehorticultural trade in the United States; it isLatin for 'tree of life' – due to the supposed medicinal properties of the sap, bark, and twigs.[5] It is sometimes called white-cedar (hyphenated) or whitecedar (one word)[4] to distinguish it fromCedrus, thetrue cedars.[6]
Unlike the closely relatedwestern red cedar (Thuja plicata), northern white cedar is only a small or medium-sized tree, growing to a height of 15 m (49 ft) tall with a 0.9 m (3.0 ft) trunk diameter, exceptionally to 38 metres (125 ft) tall and 1.8 metres (5.9 ft) diameter.[7] The tree is often stunted or prostrate in less favorable locations. Thebark is red-brown, furrowed and peels in narrow, longitudinal strips.Northern white cedar has fan-like branches and scaly leaves. Thefoliage forms in flat sprays with scale-likeleaves 3–5 millimetres (1⁄8–3⁄16 in) long.
Theseed cones are slender, yellow-green, ripening to brown,9–14 millimetres (3⁄8–9⁄16 in) long and4–5 millimetres (5⁄32–3⁄16 in) broad,[citation needed] with six to eight overlapping scales. They contain about eight seeds each.[7] The branches may take root if the tree falls.[4]
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The species was first described byCarl Linnaeus in 1753. Over 30 synonyms are listed inKew'sPlants of the World Online database.[8]
Northern white cedar isnative to an area in the southern part of eastern Canada and the adjacent part of the northern United States. It extends from southeastern Manitoba east throughout the Great Lakes region and intoOntario,Québec,New York,Vermont,New Hampshire,Maine,Prince Edward Island,New Brunswick, andNova Scotia. Isolated populations occur in west-central Manitoba, and to the south inMassachusetts,Connecticut,Ohio, andIllinois and in theAppalachian Mountains ofKentucky,Tennessee,North Carolina,Pennsylvania,Maryland,Virginia, andWest Virginia.[4] In Canada, its range reaches theArctic treeline and the southern tip ofHudson Bay. It grows mainly in places with cooler summers, with a typical temperature of 16 to 22 °C (61 to 72 °F) in July, and a shorter growing season, from 90 to 180 days.[9]
Northern white cedar grows naturally in wet forests, being particularly abundant inconiferous swamps, where other larger and faster-growing trees cannot compete successfully. It also occurs on other sites with reduced tree competition, such ascliffs. Although not currently listed as endangered, wild white cedar populations are threatened in many areas by highdeer numbers; deer find the soft evergreen foliage a very attractive winter food and strip it rapidly. The largest known specimen is 34 m (112 ft) tall and 175 cm (69 in) diameter, onSouth Manitou Island withinLeelanau County, Michigan.[citation needed]Northern white cedars can be very long-lived trees in certain conditions, with notably old specimens growing on cliffs where they are inaccessible to deer andwildfire. As of 2008, the oldest known living specimen was 1,141 years old,[10] but a dead specimen with 1,653 growth rings has been found.[11] Despite their age, these very old trees are small and stunted due to the difficult growing conditions. These individuals' long lifespans have been attributed to their slow growth and their ability to survive when different sections of the tree are damaged or killed.[12] TheWitch Tree, aT. occidentalis growing out of a cliff face onLake Superior inMinnesota, was described by theFrench explorerSieur de la Verendrye as being a mature tree in 1731; it is still alive today.
Specimens found growing on cliff faces in southern Ontario are the oldest trees inEastern North America and all of Canada, having achieved ages in excess of 1,653 years.[4]
Thuja occidentalis is commercially used for rustic fencing and posts, lumber, poles, shingles, and in the construction oflog cabins.[9] It is the preferred wood for the structural elements, such as ribs and planking, ofbirchbarkcanoes and the planking of woodencanoes.[13]
The essential oil within the plant has been used forcleansers,disinfectants, hair preparations,insecticides,liniment, room sprays, and soft soaps. The Ojibwa reportedly made a soup from the inner bark of the soft twigs. Others have used the twigs to make teas to relieveconstipation andheadache.[13]
Eastern white cedar –as arborvitae – is a popularornamental plant used in both residential and commercial landscapes.
Thuja occidentalis has important uses in traditionalOjibwe culture. Honoured with the nameNookomis Giizhik (Grandmother Cedar), the tree is the subject of sacred legends and is considered a gift to humanity for its myriad of uses, among them crafts, construction, and medicine.[14] It is one of the four plants of the Ojibwemedicine wheel, associated with the north. The foliage is rich invitamin C and is believed to be theannedda, which cured thescurvy ofJacques Cartier and his party in the winter of 1535–1536.[9] Due to the presence of the neurotoxic compoundthujone, internal use can be harmful if used for prolonged periods or while pregnant.[citation needed]
T. occidentalis is widely used as anornamental tree, particularly for screens andhedges, in gardens, parks, and cemeteries. Over 300cultivars exist, showing great variation in colour, shape, and size, with some of the more common ones being 'Degroot's Spire', 'Ellwangeriana', 'Hetz Wintergreen', 'Lutea', 'Rheingold', 'Smaragd' (or 'Emerald Green'), 'Techny', and 'Wareana'. It was introduced intoEurope as early as 1540.[citation needed]These cultivars have gained theRoyal Horticultural Society'sAward of Garden Merit:
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