This variety is eupatorium maculatum - Eastern Joe Pye Weed- and it's a big one. It grows 8 feet tall and loves ditches and creeksides. The butterflies love it. That's a Great Spangled Fritillary in the pic. It's not uncommon to see a dozen butterflies on one plant.
There are spots on the stems, which are hollow and dry beautifully. In the spring the dry stems make wonderful swords for swordfights and great duck guides - they reach all the way into the creek and are great for herding the ducks in and out of the water.
These are similar to the Spotted Joe Pye weed, which are also pink, but which have flat flower heads instead of rounded ones and are also a bit shorter at 4-5 ft instead of 8-10 ft.
