These plants are from an heirloom seed that was collected year after year by a woman in the Nashville, TN area. Bushy perennial that self-seeds. They get their common name because of the way they bloom. The flowers open in the late afternoon, typically around 4 p.m. or so, and then remain open until the next morning. Plants have grown back in spring for us even after a harsh winter. Sold as bare root plants.