Why does a Cannabis plant produce THC? This question is brought up drawing an analogy to nicotine in tobacco, where nicotine is developed by tobacco plants as a pesticide. Is THC a pesticide as well? I'm imagining that marijuana plants don't have rheumatoid arthritis.
Apparently it is used by Cannabis sativa as a type of sunscreen as it absorbs UV light https://www.reddit.com/r/trees/comments/2v79dv/science_sunday_13_wait_why_does_cannabis_have_thc/