Floating Crystalwort - an awesome floating plant, forms a dense mat across the surface.  Excellent for fish fry to hide in.  

No CO2 required, medium light, can easily be tied down similar like Java moss. 

I have worked hard to get rid of ALL the duckweed!  There is still a chance you may find a piece tangled deep within it but overall, NO DUCKWEED! (Unfortunately this tank has some snails, not many though)

This lot is for a roughly 3x3 sized piece.