What plant is that?

November’s Mystery Plant is a native perennial that grows in wet areas and reaches 2 to 5 feet in late summer. Stiff four-angled stems are topped by a bloom of many pencil-like flower spikes branching upwards, like the arms of a candelabra. Individual flower spikes have a ring of blue-purple flowers blooming from the bottom up. Leaves are opposite, lanceolate, and coarsely-toothed.