Poison ivy (PI) ranks high on our list of  noxious invasives (mile-a-minute, tree of heaven and bindweed are also in the top four).

While the mnemonic “leaves of three, let it be” is a common means of identifying PI, we also learned from a recent WPost article:

“Hairy rope, don’t be a dope” (when PI climbs trees, it grows reddish brown hairs) and

“Berries of white, run in fright ” (the PI fruits turn from green to white in the fall).

And yet another consequence of global warming – poison ivy responds to an increase in CO2 levels by growing faster and increasing the concentration of urushiol – the stuff that makes you itch.