bristly locust, Robinia hispida

And the answer is bristly locust! Remember the Golden Nature Guides? Birds, Insects, Mammals, Stars, Trees, Flowers and all the rest? Remember being a Cub Scout? Guides and scouts went together well. But that patch of purple-flowered shrubs in the neighbor's yard wasn't in the Guide, or any other book I had at the time. So many other lessons learned in the moment. And why do I remember the puzzle, and what must have been a satisfying moment when there was finally a solution? Anyway, many others knew about bristly. The Cherokee, who lived where the locust grew, found medicine and wood from it. More recently Bristly locust and its varieties became popular landscape shrubs, forming clones in many neighboring yards. Bristly has now spread to the wild in every state except AK, AZ, HI, ID, MT, ND, NV, SD, and WY, and in NS and ON. Washtenaw Co MI, 6/3/11. Bean family, Fabaceae.