I think I am thinking of the same plant, but I'm still kind of a plant newb. I've got some and it grows really well underwater, but everything I've read about it online says it surfaces; which mine has not, it just bends over at the surface like Hygro. Mine has a green to orange color on the leaves, and has grown for months submerged and has only gotten bigger.
Here is a poor pic of what I'm refering to, I think it's the same stuff..
You can see the color of the leaves, not sure if it's a natural coloration or a nutrient issue, but it has color.