Lythrum alatum (Winged Loosestrife)

From Great River and Clarence Cannon National Wildlife Refuges:

Lythrum alatum (Winged Loosestrife) is a native plant and should not be confused with Lythrum salicaria (Purple Loosestrife). The latter is an aggressive Eurasian plant that invades wetlands and forms dense stands that exclude other species. Many kinds of insects visit the flowers, including various long-tongued bees, green metallic bees, bee flies, butterflies, and skippers.