Comment: Probably not too close.

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In reply to comment: "Nigella Sativa" (see in situ)

Probably not too close.

Nigella Sativa is also know as Black Cumin or Black Caraway. The closest relative to Cannabis that I know of is Hops. (Hops and Cannabis are the only plants on earth that produce cannabinoids.)

Black Seed seems to be really cheap though:
http://www.supplementwarehouse.com/viewitem.asp?idproduct=20...