western redcedar Identification (Thuja plicata)

Check the foliage sprays, trunk, and cones on Thuja plicata.

• Branchlets form flat, fan-like sprays that hang slightly at the tips.
• Leaves are tiny, overlapping scales, about 1⁄16–1⁄8 inch (2–3 mm) long, pressed tightly to the stems.
• The crown is narrow to broadly conical, often with a strong central leader and drooping side branches.
• Cones are small and slender, about 1⁄2 inch (1–1.5 cm) long, with 8–12 thin scales.
• Older trunks show fibrous, stringy bark in long vertical strips.

Crushed foliage often helps confirm the ID if visible traits are close.

Western redcedar shows clear age-related changes in foliage, branching, cones, and trunk form.

• Seedling: Early plants carry soft, needle-like juvenile leaves instead of flat spray-like scales, with a slender upright stem and sparse side branching.
• Juvenile plant: Foliage begins mixing awl-like juvenile leaves with short scale leaves; branchlets stay finer and less flattened than on older plants.
• Mature plant: Adults form dense, strongly flattened sprays of overlapping scale leaves and a straight trunk that may broaden with a buttressed base.
• Fruiting stage: Seed cones appear at branch tips as small, oblong structures about 1/2 inch (1.3 cm) long, turning from green to brown as they mature.

Several named selections of western redcedar are identifiable by foliage color and growth habit.

• Thuja plicata 'Zebrina': New sprays are irregularly banded yellow and green, giving the branchlets a striped look unlike the plain green typical form.
• Thuja plicata 'Atrovirens': Foliage is notably darker, deep glossy green and the crown is narrower and denser than the species.
• Thuja plicata 'Whipcord': Forms a low mound, often about 4-5 feet tall and wide (1.2-1.5 m), with long, string-like drooping branchlets instead of flat fan-shaped sprays.
• Thuja plicata 'Goldy': Outer foliage stays bright golden yellow through much of the year rather than medium to dark green.

Thuja plicata stays evergreen, so it does not develop bare winter stems. In cold weather, the flattened sprays often darken to a deeper green or slightly bronzy tone. Pollen cones become noticeable in spring at branch tips, and seed cones develop by late summer to fall as small, upright cones among the foliage.

A few conifers are regularly mistaken for Thuja plicata.

Native to the Pacific coast of North America, Thuja plicata ranges from southeastern Alaska through British Columbia and Washington to Oregon and northwestern California, with inland populations into Idaho and western Montana. It is most often found in moist to wet conifer forests, stream corridors, swamps, and coastal lowlands, and also in mountain valleys. Seeing a large Thuja in cool, humid forests of the Pacific Northwest helps narrow identification toward this species.

Thuja plicata has a meaningful safety concern because its foliage and sap can irritate skin in some people, and ingesting plant material can be harmful to humans and pets.

• Skin contact: Leaves and sap may cause contact dermatitis, a skin rash or irritation, in sensitive people after handling branches or crushed foliage.
• Ingestion: Leaves and other plant parts contain compounds that can be harmful if eaten by humans or pets. This is an ingestion risk, not a routine touch risk.