Devil Grass is a drug used by the people of Mid-World. It is a grass capable of growing in most locations, including inhospitable locations like the Mohaine Desert. It is a narcotic and is very addictive. It is usually smoked, but long-time users (for example Tull's addict, Nort) may end up chewing it. These chewers have green teeth and an unpleasant odor. Roland Deschain was forced to burn the weed while crossing the Mohaine. He was careful to sleep upwind of the campfires.