ABSTRACT

Head of the Drug Information Service, St Mary’s Hospital, Portsmouth, UK

ORIGINS

The hemp plant, Cannabis sativa, is native to central Asia north of the Himalayas. It was initially confined to an area stretching from Turkestan in the west, to Pakistan in the east. Southern China probably marked the northernmost boundary of this original domain. Hemp has subsequently become much more widespread, largely due to the intervention of man. Cannabis, a dioecious species, is a member of the Cannabidaceae family, which contains only one other genus-Humulus. The hop plant, Humulus lupulus, is used to preserve and flavour beer.