Plant ID needed

[dbsmda]

I just got this plant today.
The lfs guy told me that they were unsure of the species but he said it is definitely 100% aquatic.
He said it has been in the tank there for a couple months and has been growing well.

Ive been burned buying aquatic plants before but since this was my lfs I decided to trust him.
Big mistake?

 

[Byron]

This might be Saururus cernuus, sometimes commonly called Lizard's Tail. I don't know much about this species, so it is just a guess, but the photos I have do suggest it. But not at all sure.