I found this in Old Lyme, CT at a pond. I am thinking that it might be some type of Miscanthus which I have also seen called Giant Maiden Grass. Do you agree? The plant was very tall--probably taller than my Dad. Thank you, Karl Miller
Multiple cultivars of varying heights of popular Miscanthus sinensis are sold. This looks like the seedhead of that species. However, other, taller species are also in gardens on this continent.