The common name, tall bellflower, is certainly appropriate for this attractive biennial. It blooms in mid summer with small blue flowers spaced along the top halves of the stems.
Campanula americana is native to North America. It prefers part shade with average to rich soil. The plants are tall but narrow, so space them about a foot apart to make a nice grouping. They make wonderful companion plants for late-blooming trumpet lilies. Hardy biennial in zones 4-8. Self sows.