White cedar tree

# Overview
Thuja occidentalis is an evergreen coniferous tree, in the cypress family Cupressaceae, which is native to the North east of the United States and the South east of Canada, but widely cultivated as an ornamental plant.

# Distribution
Thuja occidentalis is native to Manitoba east throughout the Great Lakes region and into Quebec, Vermont, New Hampshire, Maine, Prince Edward Island, New Brunswick, and Nova Scotia. Isolated populations exist to the south in Massachusetts, Connecticut, Ohio, Kentucky, Tennessee, North Carolina, Pennsylvania, Maryland, Virginia, and West Virginia.

# Naming and taxonomy
The species was first described by Carolus Linnaeus in 1753, and the binomial name remains current. Common names include White cedar (in the United Kingdom), Yellow Cedar, Atlantic White Cedar, Swamp cedar, Cedrus Lycea, Eastern White Cedar, False White Cedar, Hackmatack, Lebensbaum, Thuia du Canada, Techny Arborvitae, American Arborvitae or just Arborvitae, the last particularly in the horticultural trade in the United States. The name 'Arbor vitae', is Latin for "tree of life" - due to the supposed medicinal properties of the sap, bark and twigs. Despite its common names it does not belong to the cedar genus, nor is it related to the Australian White cedar, Melia azedarach.

# Ecology
Thuja occidentalis grows naturally in wet forests, being particularly abundant in coniferous swamps where other larger and faster-growing trees cannot compete successfully. It also occurs on other sites with reduced tree competition such as cliffs. Although not currently listed as endangered, wild Thuja occidentalis populations are threatened in many areas by high deer numbers; deer find the soft evergreen foliage a very attractive winter food, and strip it rapidly. The largest known specimen is 34 m tall and 175 cm diameter, on South Manitou Island within Leelanau County, Michigan.
It can be a very long-lived tree in certain conditions, with notably old specimens growing on cliffs where they are inaccessible to deer and wildfire; the oldest known living specimen is just over 1,100 years old, but a dead specimen with over 1,650 growth rings has been found. These very old trees are, despite their age, small and stunted due to the difficult growing conditions.  The Witch Tree, a T. occidentalis growing out of a cliff face on Lake Superior in Minnesota, was described by a French explorer as being a mature tree in 1731; it is still alive today.
T. occidentalis specimens found growing on cliff faces in southern Ontario are the oldest trees in Eastern North America and all of Canada, growing to ages in excess of 1,653 years old.

# Uses
White Cedar is a tree with 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 uses. It is used in craft, construction and medicine. It is one of the four plants of the Ojibwe medicine wheel, associated with the south. The foliage of Thuja occidentalis 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 15351536. Due to the neurotoxic compound thujone, internal use can be harmful if used for prolonged periods or while pregnant.
Northern white cedar is commercially used for rustic fencing and posts, lumber, poles, shingles and in the construction of log cabins,  White cedar is the preferred wood for the structural elements, such as ribs and planking, of birchbark canoes and the planking of wooden canoes.
The essential oil within the plant has been used for cleansers, disinfectants, hair preparations, insecticides, liniment, room sprays, and soft soaps.  There are some reports that the Ojibwa made a soup from the inner bark of the soft twigs.  Others have used the twigs to make teas to relieve constipation and headache.
In the 19th century Thuja was in common use as an externally applied tincture or ointment for the treatment of warts, ringworm and thrush. "An injection of the tincture into venereal warts is said to cause them to disappear."

# Cultivation
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' (a.k.a. 'Emerald Green'), 'Techny', and 'Wareana'. It was introduced into Europe as early as 1540.
The following cultivars have gained the Royal Horticultural Society's Award of Garden Merit:-
- 'Danica'
- 'Holmstrup'
- 'Rheingold'
- 'Smaragd'