There are a number of yellow flowered loosestrifes with flowers a lot like this. They have a variety of leaf patterns. None of them have purple flowers, and in fact want nothing to do with their purple namesake. This is one of the wetland group of native plants that is vulnerable to the purple loosestrife invasion. These flowers are about 3/4 inch across. They grow in AL, AR, CT, DE, FL, GA, IA, IL, IN, KY, LA, MD, ME, MI, MO, MS, NC, NJ, OH, OK, PA, SC, TN, TX, VA, WI, WV, MB, and ON. Kitty Todd Preserve, Lucas Co OH, 7/14/13.