plant ID

[Nyx]

I don't have a pic yet but will post one asap.  I need help IDing a plant. It was growing on top of a huge clump of Christmas moss that I had at the very top of my tank. It is pale green, floats and looks like a 1/2 inch thick carpet. If you try to break the mat apart, it breaks into small angular pieces. Sorry, it's not much to go on but does anyone have any ideas? I've looked here and at a few moss ID sites but can't find anything that remotely looks like it. My tank is low-tech. It's a 30 gallon with a single Coralife 55 watt CF bulb and fine black flourite sand. No CO2, just Flourish fertilizer and excel.

When I first saw this plant appear a few months ago, I thought it was the Christmas moss that was just growing too close to the water surface and didn't really pay attention but it isn't it at all. We had our first good look at it this evening when hubby finished putting together our moss wall before releasing our newest inhabitants (thank you, Ken!). So, does anyone have any ideas? As I mentioned, I will post pics sometime tomorrow. Thanks in advance for any help.

[fischkopp]

Riccia fluitans?

[Nyx]

That's it! Gee, you are good, Fischkopp!   I compared it to some photos online and that was exactly what it looks like. http://upload.wikimedia.org/wikipedia/commons/6/67/RicciaFluitans2.jpg   Thank you very much! I guess it hitch-hiked in with some Christmas moss I bought a while back. Yay! 

[Bees]

Just an FYI, I had some Riccia hitchhike in with some Hemianthus callitrichoides ''Cuba'' that I bought and it absolutely took over.  Between the Riccia and some hair algae the cuba was choked out.  My tank conditions weren't ideal for the Cuba but even the smallest piece of Riccia would grow like crazy. 

All I'm saying is that you will probably want to separate it from your moss.  I suspect the Riccia will do pretty well in your low-tech tank.

[Nyx]

Thanks for the heads up, Bees.