Sighting: Eutrochium maculatum at Windham, NH
by tracyd123 on August 26 2014
Location notes: roadside, in marshy, boggy area.
Comments: Beautiful and prolific. I understand it is an edible plant and had been used to cure typhus (fever) in colonial times. [This is unlikely to be Eutrochium purpureum based on the habitat you noted, as that species is found in upland woodlands, forests, and openings. The image appears to be Eutrochium maculatum based on the array of flower heads.]