Do you think this is a Echinodorus schlueteri ? It was sold as a Echinodorus schlueteri var. leopard, but I think it only a schlueteri.
It could be a E. cordifolius. I will look it closer tonight.I think, neither 'Leopard' nor the plant commonly known as E. schlueteri.
Btw., there is a problem with the name E. schlueteri. Jozef Somogyi, a Slovakian botanist, found out that the plant described as E. schlueteri by Karel Rataj is different from the E. "schlueteri" in the trade. J. Somogyi described the latter as E. maculatus in 2006. Therefore 'Leopard' is a cultivar of E. maculatus. The paper from J. Somogyi: http://www.springerlink.com/content/c19q7757g88330v7/
I guess, Your plant is any variant of the very variable species E. cordifolius.
I don´t see brown spots in the young leaves.The leaf tip of "false E. schlueteri" = E. maculatus is rather pointed, "apiculate", than blunt.
Do the young leaves have brown spots?
In my opinion, the real E. schlueteri and E. maculatus are very close to E. cordifolius, if not even small forms of this species.
Your plant is also quite similar to plants labelled as E. aschersonianus by aquarists, probably coming from southern South America (perhaps also little forms of E. cordifolius).
Btw., there is an information that K. Rataj grew E. maculatus (labelled as E. aschersonianus "Rubromaculatus") from seeds supposedly collected in the wild near Santa Fé in Argentina! But apparently there are no records of corresponding plants from this area.