Phragmites australis is one of the most widely distributed macrophytes in the world and a compelling model system for biological invasions as both Native and Introduced lineages grow sympatrically across North America. Decades of research on this large-statured grass and its biotic and abiotic interactions has advanced our understanding of plant ecology and plant invasions. These ecological, evolutionary, and invasion science studies have harnessed new 'omics methods and facilitated new research in molecular and chemical mechanisms of plant responses to novel and changing environments. Here we review pivotal research on P. australis ecology, evolution, genetics, and management, highlighting differences between lineages and the impacts of the invasion of Introduced P. australis on North American ecosystems.