Joe Pye Weed is a summer-flowering perennial valued for its towering presence in the garden, its large clusters of pinkish blossoms, and its almost singular attractiveness to butterflies. Given full sun and moist soil, it can grow as tall as 12 feet. The stems are hollow, so large plants may require staking. The plant gets its name from Native American herbalist Joe Pye, who's said to have used it to cure fevers. The name is applied to several members of the Eupatorium species; this specimen happens to be Eupatorium purpureum.