So Ursula, click, the giant hornbeam stump, has turned out no to be a hornbeam at all. The new leaves started opening and when they did they certainly did not look like a hornbeam should:
A post on bonsainut.com later and I believe what I have here is actually an acer rubrum. Known for its long internodes, the only saving grace is the size of the trunk will help minimize the leggy appearance. The good news is that it's popping so many buds that I have to rub them off by the dozens! It seems to want to put out shoots near the base and off of the roots. We'll keep an eye on this one and others.
If I made this mistake once, how many other trees out there could be mislabeled. Time will tell.