Chillybean, I have white snakeroot (Ageratina altissima) growing wild in my yard. It is a native wildflower that blooms in Sept/Oct in NY. I looked it up and the distribution includes Iowa. Do you want some? If so, I can add it to my swap list. It's forming seeds now and I have some I collected last year. The seed is wind-dispersed but it's easy to pull anywhere you don't want it.
