Looks like the single form of Clematis "Multi-Blue" to me...Jeanne

Here is a link that might be useful: Multi-Blue

I didn't know Multi-Blue ever threw singles. Mine never has.

BorS, do you prune your Multi Blue after the first bloom flush?

Sometimes, I've hard pruned it to the ground three or four times in the last few years. Haven't paid attention exactly to when. I don't cut it back by half every time it blooms. I don't have time to cut them back to try to get second flushes. It is all the way down or nothing. ;)

I get a second flush if I don't prune after the first.

It's weird that you don't get a second. I wonder if it's the amount of sun that allows for a second bloom.

Can anyone else weigh in here?

I'm in a warmer zone but we have far more cloudy days here than sunny ones.

I don't see those red anthers on pics of multi-blue. Maybe it's it though. filix