I've stumped the pro! He said he's never seen it and, of course, never had it for sale! Sorry to disappoint. He did think it's some form of Kamchaticum but couldn't say what is is,
I did ask if the stem could be cut in sections to get it to root and he agreed that it would work. I offered him the piece I brought along for ID and he leaped at the chance to propagate it.
