Originally Posted by Geomancer
If you look closely at Water Sprite, especially as it gets large, you can usually see bunches of roots forming all over the place. That's a new plant, you can pluck it right off and it will grow just fine (very similar to Java Fern, but Water Sprite grows much faster).
That's usually what I do, I pluck off a few and then throw away the large fern (mine is floating). Within two weeks the new plants are large themself and by week three I'm throwing them away yet again. Their growth when floating at least is the fastest I've seen with any plant.
This definitely sounds like the floating version. The folllowing pic is the planted version, Ceratopteris thalictroides.
This one is the floating version. Hah! This pic says Ceratopteris thalictroides too, so take your pick: floating or planted.
One bit of information - although both versions grow fast, the floating version would probably do the most good for the tank, having only air between itself and the lighting. It is also supposed to have access to atmospheric CO2 and use that.