Dennis It's dark and cold, and I just got warmed up after working in the yard today, so I'm not going out to the lake with a flashlight! Tomorrow I'll go look to see if I can find any Typha seedlings, and see if they look like your mystery plants. This is just a guess, but the roots and rhizome pattern look familiar. Could seed of Typha blown in from a nearby pond, creek or river? Dave Brastow Tumwater, Washington