Aller au contenu
Hub Nexus

Boston Harbor Islands National Recreation AreaPage 9 sur 104

Northern White Cedar (Thuja occidentalis)

About Northern White Cedar (Thuja occidentalis)

Northern white cedar, also known as arborvitae, is one of the few cedar species native to the northeastern United States and eastern Canada. This evergreen tree thrives in a wide range of habitats, from rocky uplands to wetlands and swamps, although it grows best in moist, alkaline soils.

The species is highly valued for its adaptability and resilience. Its dense foliage provides year-round shelter for birds and other wildlife, while its extensive root system helps stabilize soils and reduce erosion. Because of its tolerance for wet conditions, northern white cedar is often used in wetland restoration and conservation projects.

Unlike many conifers (trees that bear cones and needle-like or scale-like leaves that are typically evergreen), northern white cedar bears flattened sprays (flat, fan-like arrangement) of scale-like foliage rather than needles. This distinctive appearance, combined with its dense branding pattern, makes it a familiar sight in parks, forests, and residential landscapes.

The tree has long been important to people as well as wildlife. Its wood is naturally resistant to decay and has been used for fencing, posts, shingles, log cabins, canoes, and other outdoor structures. The common name arborvitae, meaning “tree of life,” reflects both the species’ longevity and is historical importance. Indigenous communities, including the Ojibwe, have long valued the tree for cultural, practical, and ceremonial purposes. Among the Ojibwe, it is known as Nookomis Giizhik, or “Grandmother Cedar,” and has been used in ceremonies and traditional practices for generations.

Identification

Northern white cedar is a small to medium-sized evergreen tree with a narrow, often pyramidal crown and dense foliage. Branches are arranged in flattened sprays that create a layered appearance throughout the canopy.

Rather than needles (like many other conifers), the tree has tiny overlapping scale-like leaves that cover the twigs. The foliage is bright green during the growing season and may take on bronze tones during winter.

The bark is reddish-brown to gray-brown and peels in long, narrow strips. As the tree matures, the fibrous bark becomes increasingly shaggy while remaining relatively thin.

Northern white cedar is often confused with the Eastern red cedar. To differentiate, eastern red cedar produces blue berry-like cones and has both scale-like and needle-like foliage at different stages in its life. Meanwhile, northern white cedar maintains scale-like foliage throughout its life and produces small brown woody seed cones instead of blue, berry-like cones. Eastern red cedar is considered a juniper rather than a true cedar. The small cones of northern white cedar are initially green and mature to light brown. When ripe, they open to release winged seeds that are dispersed by wind.

Phenology Highlights

Phenology is the study of recurring seasonal events in plants and animals. The following phenophases, distinct and observable stages in the annual life cycle of a plant or animal, are monitored as part of the National Parks of Boston Tree Monitoring Program.

Pollen Cones

leaves of a Northern White Cedar with cones

NPS Photo / W. Kaselow

Northern white cedar produces small pollen cones in spring. These cones are typically yellowish to tan and occur near the tips of branchlets. They are much smaller than seed cones and often appear in clusters throughout the canopy.

Open Pollen Cones & Pollen Release

Pollen cones are considered open when the cone scales separate and the pollen-producing structures become visible. Open cones often appear slightly expanded and lighter in color than unopened cones.

Pollen release typically occurs during spring as pollen cones mature. Large amounts of fine yellow pollen may be released and carried by the wind to female seed cones on the same or nearby trees. Pollen cones usually wither and fall shortly after releasing pollen.

Seed Cones

a cluster of green cones on a cedar branch

Quartl, CC BY-SA 3.0. https://creativecommons.org/licenses/by-sa/3.0/deed.en

After pollination, small green seed cones develop among the flattened sprays of foliage. Young cones are oval-shaped and upright, blending closely with the surrounding branchlets.

Ripe Seed Cones

cluster of brown seed cones on a cedar branch

H. Zell, CC BY-SA 3.0. https://creativecommons.org/licenses/by-sa/3.0/deed.en

As seed cones mature, they change from green to light brown and become woody. Mature cones are typically about ½ inch long and consist of several overlapping scales containing winged seeds.

Recent Seed Cone or Seed Drop

dropped brown, dried up seeds on the ground.

Ryan Hodnett, CC BY-SA 4.0. https://creativecommons.org/licenses/by-sa/4.0/deed.en

In late summer and autumn, mature seed cones open and release their winged seeds. Empty cones may remain attached to branches for some time, while seeds are dispersed by wind. Look for recently fallen cones or seeds beneath the tree canopy.

Learn More

National Parks of Boston Tree Monitoring Program

By observing seasonal changes in trees, volunteers help scientists better understand how plants respond to changing environmental conditions over time.

Where this belongs

  • Boston Harbor Islands National Recreation Area
  • Boston National Historical Park

Where this page came from

This page was imported from National Park Service. Produced by the U.S. National Park Service and, as a work of the United States government, in the public domain.

Nobody has written it yet — it is the source material at a new address, which is why search engines are asked to skip it and why no one earns from it. It is up for grabs: take it on, and it is yours to rewrite and to earn from.