Blue Vervain

Verbena hastata 
 
 
 
This tall perennial of wet places has lance-shaped, toothed leaves, and well-branched, strongly vertical spikes that bear small, dark blue-violet flowers. Self-seeds. Attracts bees, nectar plant for butterflies. Blue Vervain has been called a natural tranquilizer, as it was used for fevers and colds, and for insomnia.  It's external use healed sores and wounds. Most effective in mass plantings. Makes a nice, long-lasting cut flower.