Large lavender flowers resemble the annual bedding plant, Petunia. This wildflower is a perennial though and eventually forms a dense, attractive clump. Each flower lasts only a day but numerous ones follow throughout mid- to late Summer. Indigenous to open woods and prairies in the central part of North America. Use with Butterflyweed, Slender Mountain Mint, Hyssop-leaved Thoroughwort, and Coreopsis.