well i dont know about weed in general but salvia will mellow you out like an indica and if you get the salvia extract and smoke it you will trip ballz its some harsh shit tho if you try it make a throw away bong dont use anything you use for pot it will ruin it
I think what they may have meant is; what kind of plant needs the same environment / pH / EC levels etc.
I have wondered before if there is a plant i can refer to when im in grow shops that is similar in needs to cannabis.
OR even if there is a plant that can share my grow space (short thought - fuck that!) ...
meh.