Blyxa japonica is a stem plant actually, but the stems are so short to be covered by the head of leaves. Its propogated by removing the side stems and planting them, which roots and forms another plant.
It grows very well in my tank, showing moderate growth rate under high light (4wpg) with 15ppm CO2 (pH=7.0 via pH controller) and regular fertilizer additions. Iron will help it keep its green under high light, otherwise it can take a golden/brownish tint to the leaves. It is very easy to propagate. Simply uproot one that has grown dense and you will find it actually will have one or more stem offshoots. Simply pull apart the offshoots and replant. After letting one stem grow undisturbed for 1 month in my tank I pulled it apart to have four separate plants, all of them with root growth. My only complaint is that it cannot be kept short, it grows too tall to be used as a foreground plant.
I have been unable to get this plant established because my [I]Puntius denisonii[/I] (torpedo barbs, roseline sharks) would not leave it alone.
Blyxa japonica takes a little time to become truly established in the tank; however, my torpedo barbs kept pulling it up, making it impossible for it to become established. It seems the torpedo barbs like to nibble on the tips of the plants, perhaps as the tips soften after being transported and freshly planted. As the torpedo barbs nibbled, they'd inadvertently pull the plant out of the substrate. I'd then find it floating in the water soon after. This process would continue until the plants just withered away. I've tried this plant 3 times with the same results.
I think if the plants were anchored down so the torpedo barbs could not pull them up, then they would eventually become established and put out enough roots to prevent the torpedo barbs from being able to pull them up later.