2. 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
3. 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
4. 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
