Hemp plants (Cannabis sativa) being grown for their fibres, which are used to make paper and textiles. The waste products of this process can be used to make lower grade paper, and hemp seeds are a source of oil for varnishes, cosmetics and lubricants. The leaves and flowering heads of hemp, known as marijuana, contain the psychoactive drug delta-9-tetrahydrocannabinol (THC). For this reason, hemp production is strictly controlled. Hemp grown for its fibres contains much less THC than hemp grown illegally for marijuana, and has little effect as a drug.