Planted Tank Enthusiast
Join Date: Sep 2009
Location: Seattle, Washington
It is Utricularia. It's kind of a neat plant, but it becomes a nightmare in the planted tank because little pieces easily break off and grow into new plants, making it hard to eradicate. I would get it rid of it before it's too late.
That being said, you could keep it in jar by itself just for novelty's sake. It's one of the few true aquatic plants that are carnivorous, and it has a surprisingly large yellow flowered compared to its size.