Name: Bacopa monnieri|
It can be grown submersed or emersed. Emersed it has white to light blue flowers. I actually found it growing in my front yard and put in my aquarium. The leaves get larger underwater. It doesn't grow as fast as some other plants.
I have a bunch of these in my 60x30x30 cm community aquarium, they look better in bunches rather than on their own as do all stem plants. They are quite hardy and slow growing, which makes them prone to algae, but my sailfin plec and siamese flying fox takes care of this. All in all it's generally easy to look after as long as you abide by the normal rules of keeping a healthy tank.
I once owned two of these plants. Like the information said, it is an easy plant to take care of. It is a fast growing plant with root growth at leaf junctions if your water chemistry is OK. I ended up giving up on this plant not becuase it did not grow, in fact, it grow so much that it was all over the place. Not a thing you want with a thin plant with small leaves. However, if you want a fast growing plant to decorate your tank's corner then this is the plant for you.
These plants grow extremely fast once they've established themselves, however mine were decimated by my gouramis to use for nesting material. Only the stalks were left...they kept on growing though, but the stalks looked ugly so I removed the whole plants and cut away the lower bare stems and replanted them. From there it has become a cycle.
I recently purchased 2 bundles of this plant. I originally kept them bundled together and planted within the substrate. It seemed like 3/4 of them would eventually melt away at the point where they protruded from the substrate and float to the top of the aquarium. The other 1/4 seemed to send out roots from a node close to the substrate and really took off. I think it may be trial and error if you wish to plant these. A better way of growing these would probably be to tie them to a rock or driftwood. I haven't tried this method yet.
I have had a bunch of this plant for about 6 months. It grows quickly, which is good since my platies love to nibble it. And now that I have 3 dwarf gouramis I keep finding floating stems!