I have one growing up one side of a pergola. It took five years before it finally got decent growth on it, and lo, my landscape gal cut it to the ground this year! Coulda shot her.
I've seen them growing on stone walls and sturdy trellis work, but never in a tree. Just so you know, much of the growth is outwards, so it would be quite a bushy-looking vine against a tree.
A great plant, and very underused because it so slow growing, I guess. I planted a clematis a few feet away from my CH at the time, so the wait didnt bother me at all.
I just let the two vines duke it out.
Pondy

It takes a few years for this plant to get established because it spends a lot of time making roots, but once it does, it takes off. I've included a photo of climbing hydrangea climbing a tree. This photo was taken at the Nittany Inn in State College PA. I've wondered what the future is for both the hydrangea and the tree. It can climb 40-60 feet. Amazing.

{{gwi:673672}}

Thanks for the information. I'm going to have to give that some thought. I'm not sure I have enough room for one of those. It sure is beautiful growing up that tree, though.

Mary