I looked the name up after I posted the pics. Apparently, there was a Joe Pye who used this plant to treat typhus afflicting the colonists of Massachusetts Bay. He learned this from natives. The cure was successful, the herb was included in the Europeans' pharmacopoeia, and Joe Pye was thus immortalized.
A tea made from the root was drunk to prevent or dissolve kidney stones, and even to treat gout and rheumatism, both of which are associated with excess uric acid.