Clematis: What is this growing with my Clematis tangutica?, 2 by pirl

pirl wrote:
Thanks. That's a huge help.

My best guess is that it's Jackmanii. Do you recall ever buying one by that name? It does grow very tall so it seems even more likely that it's Jackmanii. That is a class/group 3 and should be pruned, very hard (down to a few inches, still showing a few leaf buds - photo attached) in early March in your area.

Here's a not so good photo of one of our Jackmanii.

Your Tangutica should go very well with Jackmanii and they are both in the same pruning class so that won't be an issue.