I haven't grown this one myself, but do you think it might be clematis virginiana? Here is a link to it on Brushwood's website with several photos. They do mention that it can be grown in shade.

Here is a link that might be useful: Clematis Virginiana at Brushwood

Thanks so much! I got really excited when I saw your post, because the flowers look right. I did more digging and I found the link below. It says that the clematis virginiana has toothed leaves. Mine has a smooth leave that's rounded at the bottom and pointed at the tip. Like I said--they're thin and very dead right now (I live in Nebraska and we have cold temps). What will sweet autumn clematis do in northern climates over winter? The plants on my porch aren't invasive at all--the flowerbeds have been neglected here for a number of years and I didn't see any sign that it had spread all over. I know sweet autumn can be very invasive and it's supposed to be evergreen. Could it be that, but more controlled in a northern climate without full sun exposure? Does it die back in northern climates and then regrow from the roots each spring? I only saw it last fall, but there didn't appear to be dead growth mixed in with the live growth then. I'm lost...that's why I have no idea how to id it.
Thanks so much!
http://www.ct-botanical-society.org/galleries/clematisvirg.html

I don't grow Sweet Autumn and have no experience with it. I've never heard that it's evergreen and will be surprised if I find out that it is. From reading this forum I know that it is usually cut all the way back in the winter and only blooms on new wood.

By the way, if you're interested here's an article on Clematis Terniflora (Sweet Autumn.

Thanks so much for the info! I know zip about clematis--I'm used to more heavily wooded, shade gardening--so I feel like I'm almost starting over as a gardener on a property with mostly full sun or light shade. I kept reading that sweet autumn clematis is evergreen, but I'm pretty sure now that they were talking about down south vs. up here. I'm guessing that has to be what I have. If all else fails I'll take it into extension or a local garden center later this year. Thanks again so much.

hi wrestlingmom, I have three sweet autumn clematis and yes they do look brown and dead each winter here. I cut mine back in spring to about 12 inches and it comes back each year. My cousin who lives two hours further north doesn't cut hers back and it get bigger each year.
roseberri