Poison Oak

Toxicodendendron diversilobum is known as Pacific poison oak or Western poison oak, even though it isn't closely related to the trees. It's leaves and stems produce an oil called urushiol, which is an allergen to 80% of people and causes the rash poison oak is so famous for. It's a staple food to many birds an forest fauna, as most animals are immune to its ill effects, including dogs. Its smoke is a particular hazard to firefighters when forests burn. Coastal Native Americans had a wide variety of uses for the plant, including drinking a tea preparation that helped make them immune to its toxin. The Ohlone weaved baskets from its stems, and its sap and ashes worked well as a black pigment for their weaving or tattoo ink.