Cannabis is a genus of annual flowering plant. Cannabis is often divided into 3 species-Cannabis sativa, Cannabis indica, and Cannabis ruderalis-but there is significant disagreement about this, and some consider them subspecies of the same parent species. Cannabis sativa can grow to 5-18 feet or more, and often has a few branches. Cannabis indica typically grows 2-4 feet tall and is compactly branched. Cannabis ruderalis contains very low levels of Δ-9-tetrahyocannabinol so is rarely grown by itself. Cannabis ruderalis flowers as a result of age, not light conditions, which is called autoflowering. It is principally used in hybrids, to enable the hybrid to have the autoflowering property. There are > 700 strains of cannabis, often with colorful names. Some are strains of 1 of the 3 subspecies. Many are crossbred hybrids. The strains can be named in a variety of ways: smell or lineage are common ways of naming. There are only a few rules about how the strains are named, and most strains' names do not follow the rules. There are 4 basic preparations of marijuana: bhang, hasish, oil (or hash oil), and leaves and/or buds. In medical marijuana trials, subjective outcomes are frequently used but blind breaking can introduce significant bias. Blind breaking occurs when patients figure out if they are in the control or the treatment group. When this occurs, there is significant overestimation of treatment effect.
Keywords: Bias; C. sativa; Cannabis; Medical marijuana.