I bought a little start of the plant several years ago at the wildflower festival during the wildflower weekend at Cheekwood, the Tennessee Botanical Garden in Nashville. All they told me was that it was a native clematis. I searched and finally found its name and some information about it. It is Bluebill, Vase Vine, Leather Flower (Clematis viorna), and what a charmer it is!
It is probably the cutest, daintiest little thing on the place. One year it took its delicate, dainty self upward growing on a bold, large Common Mullein and it was a marriage made in heaven. Never! could I have thought of such a perfect union. The tragic thing about it is: I didn't get a photograph of the two. That grieves me still. I may try transplanting a tiny mullein seedling there sometime to see if I can get a repeat.
Here are some photos to show you what I am writing and going on about. It might help to click on some of the photos to enlarge.
It has climbed...
..until the blah, green-in-summer Burning Bush (Euonymus alata) was properly decorated. By the time the shrub turns fiery red, the clematis will have fuzzy seed heads.
Seed heads green.

Seed heads fuzzy.

Stretching to the sun.
Ta-Dah! Fully decorated.
(Click for the most delightful view.)
(Click for the most delightful view.)