I did look at that but the leaves of this Clematis had pointy bits on its edge and the picture of glycyphylla seemed to have a smooth edging. I'll put up a hopefully better photo of the leaf.
I know glycinoides has just started flowering and I'm pretty sure aristata flowers a bit later. The business with toothed vs entire leaf margins is not a reliable feature to differentiate them. I go on leaf texture (thick for aristata, thin for glycinoides).