Echinodorus bleheri with a stem of runners. Eventually each of these becomes individual plants
I have bought a couple of this Echinodorus, which I find very nice and decorative and they do indeed grow fast. They look their best if they a placed by themselves and they can fill an area of the tank.
I haven't succeeded propagating the Sword plant yet, but when the runners gets roots they can be picked off and planted individually. After that it will take a while before their growth begins.