There are three plants of the toxicodendron genus that could make your life a nightmare for a long period of time. You probably know them better as poison oak, poison sumac and poison ivy. These 3 plants contain an oil that will cause a severe allergic reaction in most people. In fact, sometimes the blisters are so large that you will need to get hospitalized. The oil sticks closely to your skin, which means that you could easily spread it over your body and even to other people.
This is why, whenever you suspect these plants might be in an area where you will be working, you should wear ample protection and exercise care.
Even when dead and wilted, the oil from the plant can do damage to you. They should never be burned because the airborne toxin can travel quite a distance and cause respiratory problems in your neighbors. Instead, dispose of them in a safe manner.