I bought a pond plant at the lfs right out of the tank with the aquatic plants they were not marked or sperated, and it started to die by the next day in my tank....it was not supposed to be completely submerged.
You don't HAVE to remove the stuff, it's just better if you do, eventually as the plant grows it will restrict it, easier to do it now than to uproot the whole thing and cut it away in peices later on.
