Spotted Joe-Pye Weed

Spotted Joe-Pye Weed, Eupatoriadelphus maculatus, sometimes called spotted trumpetweed, is a hardy and fast-growing long-stemmed perennial in the aster family, indigenous to the eastern U.S. from the Great Plains to New England, and found naturally in numerous Illinois counties. It has purple stems that appear as rootlike sprouts and grow rapidly; the plant shown here grew from 1" shoots to 5 feet tall in about three months.
For more about Spotted Joe-Pye Weed and native plants for the Midwest, especially those that do well in shade/moist areas, see the "book" on this website, Gardening with Native Plants in Shady Evanston.