In case you wanted to see Echinodorus tenellus i've attached a few pictures of the Echinodorus tenellus in my tank (aka pygmy chain sword) I started with two small plants less than a week ago and already it is adding many small chains from each individual plant. The growth has been very fast.
Potamogeton looks dead right! So for all I know this is a native plant someone's been passing around as an aquarium plant. It sure does well. It also seems to like being planted in the few spots it hasn't been uprooted. I'll bet it will work as a grass in tanks. I'll keep trying to plant it and see what happens.