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Figure 1.1 
Cannabinoid biosynthesis. Arrows indicate cannabinoid 
biosynthesis pathway; dark arrows indicate established pathways; the light 
gray arrow indicates a probable but not well-established pathway 
(R. Mechoulam, Hebrew University, personal communication, 1999).11 
The great majority of studies reporting on the effects of cannabinoids 
refer to THC; most of the rest are about CBD and CBN. Other cannabinoids 
found in marijuana do not appear to play an important role in the drug's effects.

(the small leaf-like part below the flower). The amounts of cannabinoids and their relative abundance in a marijuana plant vary with growing conditions, including humidity, temperature, and soil nutrients (reviewed in Pate, 199414). The chemical stability of cannabinoids in harvested plant material is also affected by moisture, temperature, sunlight, and storage. They degrade under any storage condition.