Poison Oak (Toxicodendron diversilobum)
This small shrub is 1 to 4 feet high and is closely related to Poison Ivy. Its leaves very from red to yellow to green and blooms in march and April. Poison Oak is not a true oak, and belongs to the Sumac Family. Blistering and itching can result from contact with the oil the plant secretes. This oil can spread to clothes, shoes and pets. Generally the effects are not immediate, occurring one to two days later.