There is currently a Marijuana niche being voted on, and it has 70% approval, despite being redundant. A cannabis niche already exists.
Please go and vote down so we don't end up with a tribunal appeal.
As an aside, to @christian - who I believe is the owner of the Cannabis niche - it might be useful to add a number of other aliases for Cannabis in your description. It is good that you already have Marijuana in there, but others could help too, to improve search results in general. We should all be thinking about including important keywords in our niche descriptions - I'm realising I have not been focusing on that so much and may have to go back and revamp my descriptions!