Hemp is divided into three subspecies:
- Cannabis sativais an annual herbaceous plant in the Cannabis genus, a species of the Cannabaceae People have cultivated Cannabis sativa throughout recorded history as a source of industrial fibre, seed oil, food, recreation, religious and spiritual moods, and medicine. Each part of the plant is harvested differently, depending on the purpose of its use. The species was first classified by Carl Linnaeus in 1753.
- Cannabis indica, formally known asCannabis sativa forma indica, is an annual plant in the Cannabaceae A putative species of the genus Cannabis. In 1785, Jean-Baptiste Lamarck published a description of a second species of Cannabis, which he named Cannabis indica.
- Cannabis ruderalisis a species of Cannabis originating in central Russia. It is less common than the other species of Cannabis.
The main psychoactive part of cannabis is tetrahydrocannabinol (THC); one of 483 known compounds in the plant, including at least 65 other cannabinoids. Cannabis can be used by smoking, vaporization, within food, or as an extract.