There are no true Cedars (Cedrus) in Canada; of our two “Cedars” in Ontario, one belongs to Juniperus and one to Thuja. In Southwestern Ontario, Eastern White Cedar (Thuja occidentalis) is a common landscape tree; it is a fast-growing dense evergreen that is salt tolerant and can grow in many different environmental conditions. T. occidentalis has been used as a windbreak for hundreds of years in agriculture and as a specimen tree in our gardens for just as long. Its use against scurvy is due to its high vitamin C content, which was missing in the diets of most seafarers and explorers at the time.  Its lightweight wood does not decay easily and is used as fences and cabins, its leaves and bark are used medicinally for colds, coughs, and fevers and it is a common ingredient used in smudging ceremonies. Despite the name Cedar, Thuja is botanically very different; remember botanical names follow the classification hierarchy of Kingdom -> Division -> Class -> Order -> Family -> Genus. True Cedars and Thuja share a kingdom (Plantae), division (Pinophyta) and class (Pinopsida), but have different families and genus.  

Often referred to as Arborvitae (Arbor – Tree, Vitae – Life) usually grows to 25 meters with a single stem and tends to have a cone or Christmas tree shape. Although not a pollinator magnet like some of our flowering herbaceous and woody species, T. occidentalis has significant ecological services; it provides about a quarter of the diet of white-tailed deer and is browsed by snowshoe hare, red squirrel and beaver. It is a breeding habitat or nesting site for over 20 species of birds and an insectivore banquet for feeding warblers, redstarts, sparrows and thrush. Pileated woodpeckers are a feasting favourite on the carpenter ants that make T. occidentalis their home.

FAMILY – Cupressaceae – Kuo (equal or box): The other tree we call Cedar, the Eastern Red Cedar (Juniperus virginiana) shares a family with Thuja occidentalis. Most are aromatic and resinous with scale like leaves. This family accounts for over 90% of all coniferous trees sold in the horticulture industry and includes junipers and redwoods. Although they are mostly evergreen, they do shed their leaves every two or three years, usually in fall. The Latin name has some ambiguity to it, with two possible meanings: equal (due to its symmetrical shape) or box (due to its use as casket). The heartwood of this family is resistant to rot from water or soil as well as termites.

GENUS – Thuja – thuia or thyia (juniper, aromatic, or resinous) – There are only 5 species in this Genus, two of which can be found in Canada (Thuja plicata in the west and T. occidentalis in the east); the remaining three can be found in China and Japan. All five are known for their strongly scented leaves and bark and pendant-like branches. The word was derived from the ancient Greeks description of a similar plant and was already in use prior to Linnaeus and our current naming system. 

SPECIES – Occidentalis – from the west – We are of course in the Western World, and despite this species being in the east of Canada it holds the name “from the west”. Northern White Cedar will hold its branches to the ground and can in fact root from them, although rarely seen due to deer browse up to about 1.5 meters. The bark is fibrous and is reddish brown to gray. Identification is easy in this species as there is no other leaf like it in Southwestern Ontario; dark green scale like leaves that are flat and splayed along the twig in rows, giving it a feathery appearance. When the leaves first emerge they are much more needlelike and slowly widen and flatten out along the branch.