Marijuana is the most used illicit substance and refers to the dried leaves, stems, flowers, and seeds of the Cannabis... moreMarijuana is the most used illicit substance and refers to the dried leaves, stems, flowers, and seeds of the Cannabis indica plant Cannabis sativa. In several states, it is now permitted for medical and recreational purposes. Marijuana may provide a euphoric high, but it also inhibits short-term memory and learning, as well as the capacity to focus and coordinate. Medical Marijuana is a plant or its components used to cure ailments or disorders. It's similar to recreational Marijuana, but it's only used for medical purposes. less