Purple-stemmed aster (Symphyotrichum puniceum) is a fantastic plant for a wet site with full sun or partial shade. It is very similar to New England aster, but thrives in wetter locations and has lighter purple flowers.
Asters are keystone species that support many pollinators as both nectar sources and host plants. They are larval host plants to many specialized mining bee species (Family Andrenidae), dozens of moth species and many butterflies including the Painted Lady (Vanessa cardui) and Crescent butterflies (Genus Phyciodes).