Verbena hastata

About

Verbena hastata, commonly known as American vervain, blue vervain, simpler's joy, or swamp verbena, is a perennial species of flowering plant in the vervain family, Verbenaceae. It forms stems up to 1.5 metres tall, topped by spikes of purplish flowers. It grows throughout the continental United States and in much of southern Canada in wet conditions.

Summary from Wikipedia