This small, native bean can be frequent in sand prairie remnants. It is unusual in that the pinnate leaves are mildly sensitive, and when touched or jostled the leaflets gradually close. This phenomenon happens very slowly and is difficult to see in action.The leaf petioles each have a nectar-bearing gland that is visited by a wide variety of insects. Photographed at Liverpool Sandpits Nature Preserve in Lake County, Indiana. Long known as Cassia fasciculata, it is now being called either Cassia chamaecrista or Chamaecrista fasculata.