I would have to say that they have Cratageous washingtonian or Washington Hawthorn. I can't imagine a thornier tree in Michigan than this one. Thornes are spaced every five to eight inches and are very sharp. I've worked on them for Pruning and such and you practically have to wear Knights armour to keep from being damaged. A beautiful tree whilst blooming but certainly a pain in the side to deal with. The beauty of the flowers are worth it though. It tends toward weak branching when sharply inclined upward during winter snow/ice accumulations. Thank you for using the Ask An Expert System.