I am think it is a species of algae similar to Chara(it may just be Chara) and not a vascular plant but I could be wrong. I would PM PB forum member Bill Cody and get his advice on what it is. He is very knowledgeable in this area and can tell you whether it's sage, widgeon or an algae... I wish I could give you a confident answer but not being able to see it in person is stumping me!