Researchers studied marsh vegetation in three Connecticut River oxbows in western Massachusetts in 1974 and 1984. They found that marshes in different oxbows had distinct plant communities, with high marshes dominated by Onoclea sensibilis and low marshes by Lemna minor and Nuphar variegatum. Each oxbow had unique mid marsh vegetation zones. Marshes in younger oxbows shared species with adjacent swamp forests and remained stable over the study period. However, species richness in high and emergent zones of the oldest oxbow declined significantly over the decade.