Yup, it sure is, although I do't know what kind. It looks like some kind of hardy hibiscus to me.

Yep! It's a Hibiscus militaris - Soldier Mallow. Gorgeous blooms, huh? I'm on my second year of growing them and I love 'em.
From my limited experience, it seems to have a growth pattern simiar to Texas Star.
Barb

Thanks! Thought it was. Have had 2 of them for about 5 years or more. They sure have nice looking blooms.

I doubt that it can be H. militaris, which has a different leaf shape - see:
http://www.ionxchange.com/species_pages/h/hibiscus_militaris.html

My guess it that may be the wild form of H. moscheutos. If you do a Google image search on H. moscheutos most results are the improved garden forms and hybrids in a range of colors. But see link below, which apparently shows a wild form. Compare carefully the centre structure and coloring of the flower. I think the narrower petals in your pic are a late stage of flower opening.

Here is a link that might be useful: wild H. moscheutos