The term “cedar” refers to a group of majestic evergreen coniferous trees, but its usage spans several botanical families. While the Cedrus genus contains the species scientifically recognized as the true cedars, the common name is also broadly assigned to various species in the Cypress family, including those belonging to the Thuja and Juniperus genera. To understand where cedar grows, one must distinguish between the Old World species and the North American trees that borrowed the popular name.
The True Cedars of the Old World
The true cedars belong exclusively to the genus Cedrus, magnificent trees native to mountainous regions spanning the Old World. Their distribution is highly restricted and fragmented, typically confined to specific high-altitude zones in three major regions. These species have historical significance, particularly in the Mediterranean basin.
The Cedar of Lebanon (Cedrus libani) is native to the mountains of Lebanon, Syria, and Turkey, where it grows naturally at elevations typically between 1,300 and 2,100 meters. This tree is adapted to the region’s climate of cool, moist winters and dry summers. The closely related Cyprus Cedar (Cedrus brevifolia) is endemic solely to the Troodos Mountains on the island of Cyprus.
Moving west, the Atlas Cedar (Cedrus atlantica) is indigenous to the Atlas and Riff Mountains of North Africa, primarily in Morocco and Algeria. This species thrives in montane zones between 1,000 and 2,000 meters in elevation, occasionally forming pure stands. The easternmost true cedar is the Deodar Cedar (Cedrus deodara), native to the western Himalayas, with its range extending across Afghanistan, northern India, Nepal, and Pakistan. This species tends to grow at the highest altitudes among the true cedars, with some populations found up to 3,000 meters.
North American Trees Commonly Called Cedar
In North America, the trees commonly referred to as cedar are part of the Cypress family, not the Cedrus genus, and are often valued for their aromatic and durable wood. These species are widespread across the continent, with distributions that cover vastly different ecological zones than their Old World namesakes. The Western Red Cedar (Thuja plicata) is a prominent example, dominating the Pacific Northwest region.
The range of the Western Red Cedar stretches from the southern Alaskan panhandle south through British Columbia, Washington, and Oregon, reaching into northern California. It also has a disjunct population that extends inland, running along the west slopes of the Rocky Mountains into Idaho and Montana. This species is characteristic of the temperate rainforest environment, thriving in areas with high annual precipitation and atmospheric moisture. It is frequently found growing from sea level up to elevations of about 2,300 meters in the interior mountains.
The Eastern Red Cedar (Juniperus virginiana) possesses the broadest natural range of any conifer in eastern North America. Its distribution extends from Maine south to Florida and stretches west across the Great Plains to South Dakota and Texas. This tree is an aggressive pioneer species, often colonizing abandoned fields and rocky outcrops throughout this extensive region. It demonstrates remarkable adaptability, growing in conditions from swamps to dry soils, and is highly tolerant of drought and heat.
The Northern White Cedar (Thuja occidentalis) is concentrated in the Northeast and the Great Lakes region of the United States and Canada. Its native habitat spans from southeastern Manitoba east through Ontario and Quebec, reaching the Maritime Provinces and extending south into the Appalachian Mountains, with isolated populations in states like Illinois and Tennessee. This species is often found in lowland environments, particularly in swamps, along stream banks, and on rocky slopes where the soil is generally alkaline.
Ecological Factors That Determine Distribution
The distinct geographical locations of the various cedar species are governed by specific environmental requirements that limit their spread. For the true Old World cedars (Cedrus species), altitude is a defining factor, restricting them to montane zones with cool, wet winters and dry summers. These species are also primarily calciphiles, preferring well-drained, rocky, alkaline, or calcareous soils.
In contrast, the North American “cedars” are limited by a combination of soil moisture, soil chemistry, and fire history. The Western Red Cedar’s need for consistently high moisture and humidity restricts it largely to the coastal temperate rainforest zone. Its ability to tolerate both acidic and alkaline soils is less limiting than its climatic requirements.
The Northern White Cedar is strongly tied to alkaline or circumneutral soils, often forming dense stands in wet, calcareous swamps or on limestone cliffs. This species requires a steady supply of soil moisture. The Eastern Red Cedar, however, is a biological outlier, demonstrating exceptional drought resistance and the ability to thrive on poor, dry, circumneutral to alkaline soils. Its distribution is largely controlled by the historical absence of fire, which allows it to successfully encroach upon grasslands and open woodlands.