That's U. gibba? I wonder what the prolific bladderwort weed infesting my tropical aquarium is, then? Hmm.... I always assumed it was gibba, but it doesn't look like that pic. It's very long and stringy, hardly ever branches. I thought it was a weird type of algae for the longest time, and kept trying to get rid of it, but it somehow always comes back. It will attach to a plant or something and then just grow, straight out horizontally, with occasional nodules (which i now realize are traps) on an otherwise featureless "stem". Any ideas?