It’s fall in Wisconsin, and that means that white snakeroot (Ageratina altissima) is everywhere.
Depending on the weather it may be around until nearly December, long after the asters and goldenrods have gone.
I threw out that binomial all authoritative-like, but EOL gives thirty-three synonymous binomials for it that have been used at various times and places. The USDA’s PLANTS database, a little more conservatively, only five. The “L.” afterwards indicates that this was one of the species in Linnaeus’ Species Plantarum, in 1753; so that gives two hundred years of science even before there was any such thing as genetics.
They have a statue of Linnaeus in Chicago, apparently. Doubtless there is white snakeroot all about it right now.