Hi Snasxs..I purchased this plant at a local nursery, planted in the garden. It's called Alternanthera, think the spelling is correct. I actually bought a few plants that, come autumn, are coming indoors. Oddly, some nurseries sell Alternanthera as house plants..a lot more $ than when sold as an annual.
It's a beautiful plant. Are you growing yours in a pot or outdoor garden? Toni

The yellow is in this thread: http://forums2.gardenweb.com/forums/load/houseplt/msg0813403331456.html

I think these are actually Amaranthus, though the coloring of this one could be easily confused with Alternanthera.