Due to the relatively small population that we have here I think it would probably be best to keep as broad a spectrum as possible.
There will most definately be plant specific trades, discussions, etc... But it might be a bit too early to start specifiying down to that level exclusively.
Maybe have it something along the lines of the "Greater Victoria Fish and Aquatic Plant Enthusiasts" or something along those lines..?
Or "Vancouver Island Fish and Aquatic Plant Community" - VIFAP?