Exotic, beautiful, invasive.
There is a clump of this stuff that grows in the Tamarac National Wildlife Refuge and I first made it's acquaintance in the summer of Y2K. It was blooming profusely, but looking somewhat forlorn as it was the only one of its kind amidst a vast expanse of cattail, sedges, and wild rice. I determined to prevent it from spreading, so cut off its flowers, stuffed them into a sack and deposited them in the local landfill.
Each summer I visit the site and do some mayhem to this persistent plant. It has been pulled out by the roots, cut down to ground level, had its flower heads removed, even shoveled out one year when I was more ambitious.
It has not spread, but comes back every year. I cut off the flower heads again this year - twice !!