Pacific Poison Oak

Description:

Woody, sparse bush with bracts of tiny white flowers with yellow stamen. The leaves are lobate and grow in threes.

Habitat:

Oak forest along trail at Blue Sky Ecological Reserve. "Western poison oak is found only on the Pacific Coast of the United States and of Canada. It is one of California's most prevalent woody shrubs, but also climbs, vine-like, up the sides of trees, and can be found growing as single stems in grassland, often as part of early stage succession where woodland has been removed, and serving as a nurse plant for other species." - Wikipedia

Notes:

Poison Oak is "best known for its ability to cause allergic rashes after contact. The plant alkaloid produced by members of the genus Toxicodendron, called urushiol, is known for causing an uncomfortable, and sometimes painful, skin reaction. Urushiol is the main component of the oily resin that is found on the stems and leaves of poison ivy and several other related species (Hogan, 2008). It causes contact dermatitis — an immune-mediated skin inflammation (Kalish et al, 1994) — in four-fifths of humans." - Wikipedia