Rotala macrandra ‘Green’ Confusion

You may remember this picture that I took of Rotala macrandra var. ‘Green’ last year at my friend Aaron’s house. He had it growing beautifully in his ADA 90P aquarium. Notice how the leaves are slight, with some hooked edges, and somewhat transparent.

Now, take a look at the picture below. This is the same plant in my 40G tank. The leaves are rounder, thicker, and lacking the spiked edges. Why the difference? Well, about 2 months ago, I got lazy, and didn’t trim this tank, allowing the R. macrandra var. ‘Green’ to grow emersed from the water. Then, I finally performed a water change, raised the water levels, and replanted the tops of the stems, submersing them.

This also coincided with a significant increase of light when I upgraded to the AHSupply 2x96W kit. Since then, the emersed growth form of the Rotala has continued, even though it has been persistantly submersed. I would have figured that the lesser CO2 levels of the water verses the atmosphere would have triggered the plant to convert to its’ submersed form, but apparently not.

I’m still deciding which form I like best. Has anyone else experienced this phenomenon before?