I think maybe your plant is Glossostigma elatinoides. (EX:
http://naturalaquariums.com/plants/glosso.html; http://www.darkwhite.info/images/pla...latinoides.jpg
I think all of the Marsilea species (there's like 45, I think) have clover like leaves. Yeah, I just found this info on wiki:
http://en.wikipedia.org/wiki/Marsileaceae
Here's a pic of one of my Marsilea:
Marsilea quadrifolia