"Sway"

Several days ago I was doing quite a bit of photography along some areas of the Huron River. The water level is much lower now than it usually is this time of year, but for some reason there are many more plants along the river that I haven't seen before. This is one of them. I have no idea what it's called, but it is quite long and spindly. The flowering part is only at the ends, which might have made it a bit top heavy, so it swayed in the wind. It almost looks like it's flowing, and flowing in the opposite direction than the river. As always if you know what this plant might be, feel free to let me know! :)