Twin Leaf, Jeffersonia diphylla.
Just one day after blooming most of the petals have already fallen off.
Note how the anthers were pretty much already self pollinating the plant when the flower opened. I believe this is why the flower doesn't last as long. This begs the question, why bother flowering at all? Last year I had only one plant flower and it went on to produce an acorn sized seed pod that popped open, though not enough to say this plant spreads by launching it's seeds. Seeds have elaiosome on them, but not a whole lot. Elaiosome is a substance attached to seeds to get ants to haul them back to the nest. An issue though it's the size of the elaiosome is a direct indicator on the quality of the seed it's attached to. When pollination is poor the elaiosome pocket will be smaller. In this case the Twinleaf seeds had really tiny pockets of elaiosome, I'd say smaller than 1/20th the seed mass. That's asking a lot even for an ant though I imagen something may have found it tasty enough to drag a few inches.