Hi,
Although Tropica plants are disallowed in the US you may want to check their website for identification although they don't always show the emersed state=> Tropica

There are one or two Asian vendor websites I find helpful as reference because of the accuracy of the photos: My favourite is AquaspotWorld=> http://www.aquaspotworld.com/index.php?session=24e504a9df9dd6e785a27324114dfee0

Emmersed P. Stelleta should be needle leafed often with serrated edges. Here is a Tropica version 1 week or so after planting. Other than being a bit taller their form is pretty much what it was at planting:


Cheers,