A great shrub for moist soils or even in standing water along the edge of a pond or lake. Glossy green leaves and interesting flowers make this a favorite for wetland areas. Full sun is best but grows reasonably well in shadier locations.
Red Maples, Sycamore, Swamp White Oak, Shellbark Hickory from personal observation.
We have seen this plant growing in the dense shade of a flooded pool in a forest. The area itself probably did not receive any direct sunlight. Growing alongside the Buttonbush in the sticky muck was Skunk Cabbage. The round flowers are quite distinctive and lovely.