SERIES: DRUGS UNCOVERED: THE FACTS: CANNABIS

There are three sub-species of cannabis plant - Cannabis sativa,
Cannabis sativa indica and Cannabis sativa ruderalis - but it is the
indica sub-species that provides the majority of the world's skunk,
hash, kif or marijuana. The key components of the drug are THC
(delta-9-tetrahydrocannabinol) and CBD (cannabidiol).

After cannabis is smoked, the THC acts on cannabinoid receptors in
the brain, affecting memory, concentration, and perception and
movement. The effects last three-to-four hours.

Cannabis costs anywhere between UKP 55 and UKP 134 per ounce.

Last month, a study by the Beckley Foundation found cannabis is less
harmful than both alcohol and tobacco.

The use of cannabis by humans has been traced back as far as the
Mesolithic period (around 10,000BC).

Queen Victoria was prescribed cannabis to calm period pains.

1936 saw the release of over-the-top anti-marijuana film Reefer Madness.

Indian tradition says the gods sent man cannabis so he might attain
delight, courage and heightened sexual desires.

There are thought to be 140 million cannabis users globally (about 2
per cent of all people), making it the most popular illegal drug.