I almost forgot the name of this plant when I found it blooming last weekend.
Despite the fact that the flower is not bell-shaped, this plant is called tall bellflower (Campanulastrum americanum). The flowers are a pretty shade of cornflower blue and have an ornate pistil arrangement that looks like a stripped down version of the purple passion flower, also known as maypops.
Here are side-by-side close-ups of maypops and tall bellflower so you can see what I mean.
The stems in the first photo are in an unusual arrangement. They're bunched because a vine wrapped the three together. Click here for a more typical view.
(tall bellflower photos by Kate St. John. Maypops from this page at Wikimedia Commons)