Cannabis plants (Cannabis sativa) growing in an illegal nursery. These plants are being grown for the production of marijuana, the dried flowering heads of the plants. Marijuana contains the psychoactive drug tetrahydrocannabinol (THC), and is usually smoked or eaten. THC produces feelings of elation and amusement. It can alter the perception of time and also causes increased appetite. Side-effects can include a dry mouth and eyes, paranoia and a lack of co-ordination. The plants seen here are skunk, a particularly potent form of the plant with a high THC content. Cultivation of Cannabis sativa is illegal in most countries.