: From the WI Edu. plant database I'd swear that it was Echnodorus berteroi. It was growing emerse, about 2ft. tall with numerous flower spikes that were 3ft. tall. I dug a couple up last fall, put them in my pond, and they seemed to die. A week ago I was exploring in the same area (Milwaukee Co.) didn't find anything, it was still pretty cold here (40's) so I looked in my pond(had to break the ice) and sure enough there was green growth on the sword, so I put in my tank. The growth has been amazing.