Identifying poison ivy

Leaves of three: It almost always has clusters of three leaves, as seen here. But it’s not the only plant like that, so look for other characteristics.
Size: The leaf sizes vary, but at maturity are between two and four inches long. The middle leaf tends to be larger than the other two.

Sometimes the leaves are rounded.

Sometimes they are notched.

The leaves are never serrated.
This is not poison ivy.

Shiny or not? It is a misconception that poison ivy leaves are always shiny. They are often dull.

End of the season:
The leaves will turn red or orange in the fall, but remain poisonous even after falling from the plant. The stems and roots will also still have poison oils on them, so cover all exposed skin before attempting to remove poison ivy that has died down.

How do you get it?
The oil secreted by the plant causes an allergic reaction leading to itchy rashes of varying severity.
Direct contact: Touching any part of the plant with bare skin, including leaves, stems, and roots.
Indirect contact: Don’t touch anything that came in contact with the plants — like clothing or animals.

If you touch it
Remove oils: Within an hour, rinse with lots of cold water. Do not use hot water initially. Try, wiping exposed areas with alcohol.
Treatment: Rashes last for up to three weeks. Anti-itch creams are available over the counter. See a doctor for severe rashes.

What about pets?
Animals are not affected by poison ivy, even if they eat it. But don’t touch their fur if they’ve been playing in poison ivy.

Can I be immune?
Some people are, but the immunity can come and go.

Getting rid of it
Spray leaves with a strong herbicide or carefully cut the stem at the ground. Never yank the plant out by its roots, never use a weed whacker, and never burn it — the smoke is toxic.

SOURCES: University of Massachusetts; Jon Sachs,
David Schutz, Daigo Fujiwara/ Globe Staff