The Black Ring

Black ring of poison ivy vine

This is a photo of a poison ivy vine that was chainsawed along with the tree that it was climbing upon.

Notice the black ring around the small round vine: that is the urushiol oil of the poison ivy vine that has turned black after exposure to air. Very few plant saps turn black like this, so it is a good way to determine if a vine is poison ivy or oak. It takes about a hour to dry and turn black.

When this vine was sawed, it likely spewed a fair amount of sap, possibly on the person doing the sawing. And if one were to burn this log, the smoke would carry a good amount of urshiol soot, which when breathed in can cause terrible problems.