“Cannabis sativa L. (Cannabaceae) is an important medicinal plant well known for its pharmacologic and therapeutic potency…

These plants are selected to be used in mass cultivation for the production of biomass as a starting material for the isolation of THC as a bulk active pharmaceutical.”

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3550375/

http://www.thctotalhealthcare.com/category/thc-delta-9-tetrahydrocannabinol/