Codonopsis lanceolata, perhaps.

Here is a link that might be useful: {{gwi:203409}}

I remembered to look at my codonopsis this evening and it sure looks the same to me.
Remy

We did reply some time ago on this.

I never got the ID on this one, just the Ampelopsis Brevipedunculata which you ID'd. Someone suggested that this was a mile a minute vine but that was incorrect. Other then that there were no guesses until Remy suggested the codonopsis. I'm still waiting on that darn bud to open. It's taking forever!