When to prune hydrangeas? | Hydrangea Pruning Masterclass | Bates Botanical Bootcamp 

That's a good guess, from our investigations it appears early American taxonomists thought the shape of the leaves resembled tree leaves and the overall branchiness of shrub looked like a small tree.

@@batesnursery that's very interesting but kind of a bummer - tiny tree flowers is way more fun!!

Growing up in PA, my next door neighbor had one of these that was straight up a tree. I think the thing must have been 100 years old, but it was about 20 feet tall on a woody tree trunk. Tons of flowers every year that brought every bumble bee around!

@@graphicnightmares3546 We would love to visit that specimen!