How do I identify it?

Look for leaves of three, which can be glossy or dull and vary in shape.

Is it safe to touch if I wear gloves?

Urushiol is persistent and can remain on clothing or tools for years, so extreme caution is required.

Plant guide

Pacific poison oak.

Toxicodendron diversilobum

Pronounced tox-ih-koh-DEN-dron dy-ver-sih-LOH-bum

Also known as Pacific poison oak, Pacific poison-oak, poison oak, western poison oak, western poison-oak

Toxicodendron diversilobum — Photo by Hannah Stitt (CC BY) via gbif

This native shrub is well known for causing severe skin rashes upon contact. It plays a vital role in local ecosystems by providing food and shelter for wildlife. You should avoid touching this plant entirely to prevent allergic reactions.

At a glance

Care level: Easy
Plant type: Deciduous shrub
Light: Full sun to partial shade
Indoor light: Bright indirect
Water: Every 7 to 14 days
Mature size: 1 to 4 meters
Growth rate: Medium
Hardiness: USDA 6 to 10
Bloom time: Late spring to early summer

Care

This plant thrives in the wild without any human intervention. If you encounter it in your landscape, wear protective gear to remove it safely. All parts of the plant contain urushiol year round, including dull leaves and leafless winter stems, so treat every part of it as hazardous.

Watering: It is highly drought tolerant once established in its natural habitat.
Feeding: This plant does not require any supplemental fertilizer.
Pruning: Pruning is not recommended due to the high risk of skin irritation from the plant oils.
Repotting: This plant is rarely kept in containers and should be handled with extreme caution if repotting is necessary.
Soil: Well draining soil
Soil pH: 6.0 to 7.5
Temperature: -15 to 40°C
Humidity: 30 to 70%
Drought tolerance: High

Safety

People: The plant contains urushiol, which causes severe contact dermatitis in most humans.
Pets: Dogs and cats rarely get a rash from this plant because their fur protects their skin, though thinly furred areas like the belly or nose can react. The bigger risk is urushiol on their coat rubbing off onto people, so wash pets while wearing gloves after contact. Eating the plant may cause mild stomach upset.
Children: Keep children away from this plant as even light contact with leaves or stems can cause a significant allergic reaction.
Contact allergens: The sap contains urushiol, which causes a painful, blistering rash upon contact.
Airborne allergens: Burning the plant releases urushiol in smoke, which can cause severe, life threatening lung irritation.
Edibility: All parts of this plant contain urushiol and are strictly non edible.

How to identify it

Leaves usually in groups of three
Leaflets have lobed or wavy edges
Glossy or dull green foliage
Turns vibrant red in autumn
Small greenish white flowers

Height: 0.5 to 4m
Spread: 1 to 5m
Leaves: green, red, yellow, deciduous
Flowers: white, greenish, 0.5 to 1cm
Fruit: white, tan, Autumn

Problems to watch for

· It is a highly resilient native species that rarely suffers from pests or diseases.

By symptom

Plant problems by symptom

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Growing it

Propagation: seed, rhizome division
When to plant: spring, autumn

It is best to observe this plant from a distance rather than including it in a managed garden.

Grows well with

Coast Live Oak · They frequently grow together in coastal scrub and woodland habitats.
California Sagebrush · This shrub often shares the same dry, sunny slopes.

Similar species

Fragrant Sumac · It has similar three-part leaves but lacks the toxic urushiol.
Poison Ivy · It is a close relative with similar toxic properties and growth habits.

Science

Family: Anacardiaceae
Genus: Toxicodendron
Order: Sapindales
Class: Magnoliopsida
Native range: Western North America from British Columbia to Baja California.
Conservation: This plant is common and not of conservation concern.

It thrives in diverse habitats by spreading through underground rhizomes and climbing trees to reach sunlight.

Value to wildlife: nectar source, berries for birds, nesting cover
Pollinators: bees, butterflies, beetles
Uses: wildlife habitat, erosion control

Through the year

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Flowering

Fruiting

Foliage

Ecological indicators

Salinity: 2/9
Soil reaction: 5/9
Light: 6/9
Temperature: 6/9
Moisture: 4/9
Nutrients: 3/9

Taxonomy resolved against GBIF.

Questions people ask

How do I identify it?: Look for leaves of three, which can be glossy or dull and vary in shape.
Is it safe to touch if I wear gloves?: Urushiol is persistent and can remain on clothing or tools for years, so extreme caution is required.

Where the name comes from

The genus name comes from Greek words meaning toxic tree, while the species name refers to its variable leaf shapes.

Good to know

The leaves often turn brilliant shades of red and orange in the fall.
Native American tribes historically used the sap for basket weaving and as a dye.
Birds readily eat the berries despite the urushiol content.
It is closely related to poison ivy and poison sumac.

Also in

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This guide was generated with AI on September 26, 2026 and checked against GBIF taxonomy. It is general information, not horticultural or veterinary advice. Read about how we build these guides.