Identify Friday's Fabulous Flower

This tree in flower isn’t particularly gaudy, but it takes lots of people by surprise, including a couple of my plant taxonomy students. So have a look, and then decide what pretty common and well known plant family does this plant belong in? It’s a bit hard to see, but there are 10 stamens. You get extra credit for getting the name of the plant. Give me your answer before you read on.

This one catches many people by surprise because it really doesn’t look much like a member of the bean family (Fabaceae). In its broadest concept the bean family consists of three big subfamilies, the faboids with the typical bean flower, the mimosoids with flowers in powder puff inflorescences, and the caesalpinioids, which being largely tropical are less familiar to residents of temperate climates. And this species has none of the floral flamboyance of Delonix regia, the royal Poinciana. Most people even fail to notice this tree is in flower, but it has the handsome broad spreading crown of its tropical relative. And several of my students correctly identified this as Gymnocladus dioica, the Kentucky coffee tree (but they were using a plant ID manual).