Poison Oak

Rhus diversiloba

Characteristics

• Tall shrub or tree climbing vine• Dark, shiny green leaves acquire shades of

red and yellow in the fall• Pinnately compound, “leaves of three will

poison thee”• Grayish, white berries persist after leaves

have fallen

Ecology

• West side species, although found in river valleys of Eastern Oregon when elevation permits

• Common in Rogue Valley on hillsides and dry ridges with western and southern exposure

• Where summer precipitation is sufficient, other plants out compete poison oak which then disappears

• Klamath River Canyon downstream of raft put in

Ecology continued

• Oils on plant are toxic• Immunity relative, with some individuals changes

during life• Twigs and leaves have toxic oils• Horses, cattle, deer and elk browse the plant with

immunity• Pets often carry toxic oils and spread to people• Burning fumes are especially toxic

Variation in leaf