I have no idea! Looks nice though. One issue is that emersed (out-of-water) growth forms can look very different, in terms of leaf shape and stem thickness, from plants grown immersed (under water). I don't recognize the plant, but then again, there are lots of plants I can't ID! If the plant fades over time, well... then oops. Just enjoy it in the meantime and see what happens.
Since I see lots of nodal rootlets coming out, I bet it's aquatic, but that's just my hypothesis.
I bet someone here can ID it for you.