(NEXSTAR) — The definition of a weed is relatively vague — a plant growing where you don’t want it, experts explain — but some earn an extra adjective to describe them: noxious. That term has a ...

Many harmful weeds, such as poison ivy and poison oak, contain urushiol, causing rashes and blisters. Weeds like giant hogweed and wild parsnip produce sap that can lead to severe skin burns upon ...