These are giant reed plants. They grow about 20 feet high along our road in the swampier creek areas. They top out into huge feathery plumes that look like foxtail on steroids. A truck had swiped against one of the reeds so this bloom was hanging low.
I went back with clippers and snipped a few plumes to dry for indoor display. I'm going to have to be careful not to let the seeds out into the yard as this plant would LOVE to get its roots pond side.