A Belle Fleur

Meet the Tall Bellflower (Campanulastrum americanum), a.k.a., American Bellflower.  Interestingly, it's not a bell-shaped flower, being instead rather flat.  According to Wildflowers of the United States, tall Bellflower appears to have 5 blue petals, but those are actually lobes of the corolla rather than real petals.

This specimen was growing along the rail trail between Opekiska Lock & Dam and the Uffington Marina.