It's a bulb plant. Sort of like a crispus. I just can't spell the name for the life of me. >_<
If you look up "aquarium bulb plants" you will see them right away. If you pollinate the flowers you can sometimes get new baby plants from the tiny black seeds. I've kept a whole lot of them over about 10 years by doing that. I currently have about 4 baby plants and mine are also flowering. The flowers must be allowed to go just above the water.