Which plant species is commonly called poison ivy?

Toxicodendron radicans is the plant species commonly called poison ivy.

It is a woody vine or shrub native to North America and parts of Asia. The plant produces urushiol, an oily mixture that can trigger an itchy allergic rash in susceptible people after contact.

Poison ivy is highly variable in appearance. Its leaves may grow as three leaflets, and the plant can climb trees using aerial rootlets or spread along the ground. The familiar saying “leaves of three, let it be” is useful but not a complete identification rule.

Poison ivy is often confused with poison oak and poison sumac, which are related Toxicodendron species. Burning the plant is dangerous because urushiol can be carried in smoke. The oil may also remain on clothing, tools, or animal fur.