Poison ivy

Poison Ivy  is a plant that mentioned in Diary of a Wimpy Kid: Old School.

When Mr. Jefferson sets up a fire and told the rest of Greg's cabin mates to get some kindling for a fire but nobody knew what kindling was, so they brought back everything as they thought might burn. His son Rowley came back with what looked like a bunch of weeds and tossed them onto fire, but that totally smothered it. It turns out the weeds Rowley put on the fire were actually poison ivy, and the next morning he woke up covered with spots. His father Mr. Jefferson woke up too and he discovered that he had trouble breathing as he inhaled the fumes and gotten it in his lungs. The nurse called Mrs. Jefferson to come pick them both up and they're done for good. Greg mentioned that The Essential Book For Young Lads had a chapter on how to identify poison ivy, which would have come in handy yesterday for Rowley and Mr. Jefferson.