Poison Oak is a woody perennial weed that grows as an upright shrub in full sun or a creeping vine in shadier areas. The green, oval, lobed leaflets are 1 to 4 inches long in groups of three. Clusters of greenish flowers form in spring. Leaves turn reddish-orange in fall. Poison Oak oil, which causes rash and irritation, is most prominent in spring and summer, but can cause rashes year round.
Hand-pulling and burning Poison Oak is not recommended. The roots will produce new plants, and the oil can vaporize when burned, irritating lungs and eyes.
Poison Oak is most common west of the Rocky Mountains.
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