I bought those two plants from my LFS in the last three weeks. One was labelled Red Ludwiga and the other wasn't labelled at all. I had a feeling it was a Ludwiga species but I couldn't find any pictures that matched it until today. What's really interesting about the "green" variant is that the underside of the leaf turns pink/red while the top side of the leaf stays green. My 'red' looks more brown, but i think that's because of my 6700/10k lighting.