Blue vervain grows in wet meadows, river bottomlands, stream banks, slough edges, fields and waste areas across most of the United States and southern Canada, including Quebec. It sometimes forms small colonies, and NatureServe rates it Secure. Its flowers are visited by bees, and it is a larval host for the common buckeye butterfly, the verbena moth and the verbena bud moth.
The epithet hastata is Latin for spear-shaped, referring to the leaf base. Common names include American vervain, swamp verbena and simpler's joy. It has a long history of traditional medicinal reputation, but this guide gives no use instructions.