Hello ! I posted a picture of the flower of this species some time ago, but I have now photographed the leaves and seed heads as well, if that will make identification easier. The hits you get on Clematis ochotensis on the web look very different from my plant, but the pictures in Magnus Johnssons book on Clematis look much more alike my plant, even though the flowers are darker. I got the seeds from Alexandra Berkutenko in Magadan many years ago. I think she has stopped selling seeds now.
Here are all the pictures:
