Butterfly Magnet

I can't find this bushy bloom in any of my flower books, but hopefully someone else knows its name. I noticed it growing all over southern Ohio and northeastern Kentucky, and it's a butterfly magnet (like our Butterfly Bush in the northwest). This one flower head had 7 butterflies on it; there were probably 2-3 dozen spread out on the plant. If it grows in my zone, I'm planting them!