It looked like it was a species of a plant called hygrophila. Some stores will bog plants (like this sp. of hygro) that can adapt to the changing levels of water when the bog floods, but can't be kept fully submersed for too long or else they die off. Normally these plants will be fine if a good portion of the plant is above the water. A good indicator to if a plant is semi-aquatic or not aquatic at all, is if it stands up straight when outside of the water, although some aquatic plants may do this (like possibly swords.)
