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Anthriscus caucalis >

Poison Oak
Toxicodendron diversilobum

Family: Anacardiaceae (SUMAC, CASHEW).
Other common names: Pacific poison oak, western poison oak.
Generic common name: POISON OAK, POISON IVY.

Circle X Ranch: Grotto Trail, riparian woodland, March 2004.

Characteristics: Native, White, Small, Clusters, Simple, Woody, Perennial, Early Spring.
Thumbnail Picture of Toxicodendron diversilobum

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Expect Poison Oak in shaded and sheltered areas. It is often under trees and along the banks of streams. In the winter it loses its leaves but the bare stems are potent irritants as well. It is a fast growing plant and is frequently one of the first to crowd the margins of a trail once vegetation starts to close in again.

Remember the jingles
Leaves of Three: Leave It Be
Berries White: Awful Sight.

Small white flowers in the Spring (these are male.)


There is a huge variation in leaf size and shape.

The leaves are often shiny (unless covered with dust.)

New leaves are often reddish.

An unusual plant with some leaves having more than three leaflets.

Another with more than three leaflets. Many similar plants in the vicinity.

Another unusual plant in which some of the individual leaflets become lobes of a single leaf.

When it takes the form of a climbing vine it can appear overhead on trails by dropping down from above.

A large tree inundated by vines.

When the vines become long they can grow to a good girth.

Dense, thick growth along both sides of a trail.

Fall colors and white berries.

Compared with Basket Brush

Compared with Leather Root

Compared with California Blackberry

Compared with California-tea

Compared with Virgins Bower

Mixed With Virgin's Bower on Toyon

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