Thuja occidentalis, also known as northern white-cedar, eastern white-cedar, or arborvitae, is an evergreen coniferous tree, in the cypress family Cupressaceae, which is native to eastern Canada and much of the north-central and northeastern United States. and eastern arborvitae. It is sometimes called white-cedar (hyphenated) or whitecedar (one word) to distinguish it from Cedrus, the true cedars.

Description

Unlike the closely related western red cedar (Thuja plicata), northern white cedar is only a small or medium-sized tree, growing to a height of tall with a trunk diameter, exceptionally to tall and diameter. The tree is often stunted or prostrate in less favorable locations. The bark is red-brown, furrowed and peels in narrow, longitudinal strips.

Northern white cedar has fan-like branches and scaly leaves. The foliage forms in flat sprays with scale-like leaves long.

The seed cones are slender, yellow-green, ripening to brown, long and broad, with six to eight overlapping scales. They contain about eight seeds each. but a dead specimen with 1,653 growth rings has been found. 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. The Witch Tree, a T. occidentalis growing out of a cliff face on Lake Superior in Minnesota, was described by the French explorer Sieur de la Verendrye as being a mature tree in 1731; it is still alive today.

thumb|upright|Old trees growing on a rock ledge in [[Potawatomi State Park, Wisconsin]]

Specimens found growing on cliff faces in southern Ontario are the oldest trees in Eastern North America and all of Canada, having achieved ages in excess of 1,653 years. Due to its rarity, eastern white cedar is listed as vulnerable under the Nova Scotia Endangered Species Act.

Uses

Thuja occidentalis is commercially used for rustic fencing and posts, lumber, poles, shingles, and in the construction of log cabins.

Eastern white cedar – as arborvitae – is a popular ornamental plant used in both residential and commercial landscapes.

Thuja occidentalis has important uses in traditional Ojibwe culture. Honoured with the name Nookomis 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. It is one of the four plants of the Ojibwe medicine wheel, associated with the north. The foliage is rich in vitamin C and is believed to be the annedda, which cured the scurvy of Jacques Cartier and his party in the winter of 1535–1536. Due to the presence of the neurotoxic compound thujone, internal use can be harmful if used for prolonged periods or while pregnant.

Cultivation

thumb|A grove of a columnar ornamental variety in [[Powsin Botanical Garden, Warsaw, Poland]]

T. occidentalis is widely used as an ornamental tree, particularly for screens and hedges, in gardens, parks, and cemeteries. Over 300 cultivars 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 into Europe as early as 1540.

These cultivars have gained the Royal Horticultural Society's Award of Garden Merit:

  • 'Danica'
  • 'Golden Tuffet'
  • 'Holmstrup'
  • 'Rheingold'
  • 'Smaragd'

See also

  • Chamaecyparis thyoides

References

  • University of Michigan at Dearborn: Native American Ethnobotany of Thuja occidentalis
  • Borealforest.org: Thuja occidentalis