My family owns a nursery in Maryland that has been in business for 95 years. My Grandfather received one of these from a USDA program that got them from pre-war China. Planted in the backyard it was easily 50’ when I was a kid and easy to climb.
Outside Bessey Hall at MSU there was a tree, offspring of a single living specimen found by a British exploration of the Chinese interior. To keep the species viable, various colleges and whatnot cultivated it all over the world, and MSU has a beautiful campus, thanks to its roots as an ag school.