if you want more than educated guesses, some more pics would be helpfull.

Are there ever any flowers/ seedheads on this plant? a pic even of the old ones could help,

then flower stalks

and the leaves, especially where the leaf sits on some stalk, so where it starts

do you cut it back in spring?

Thanks. i posted a couple morr pictures including left over stems from last year. i have been cutting back in the winter