Poison Sumac

The toxic principle is a phenolic compound called urushiol. It is a skin and mucous
membrane irritant and is found in all parts of the plant. Some humans are quite sensitive
to the effects of the toxin while others show no ill effects from coming into contact with
the plant. The toxin has little or no effect on animals, but pets may carry the irritating
substance on their hair and thereby transmit it to humans.
Susceptible humans exhibit intense itching with inflammation and the formation of
blisters at the areas of contact. Animals are rarely affected. Burning may be dangerous
because the irritant may be transmitted by smoke.