The North American Coastal Plain (NACP) in the southeastern United States was initially overlooked as a biodiversity hotspot in multiple analyses of global biodiversity because it was assumed that the NACP would not support high species diversity. As a result, the same investigative efforts to document and preserve biodiversity have not been given to this center of endemism as other hotspots. The NACP exhibits particularly high freshwater biodiversity and is home to many endemic aquatic plant species. Endemic organisms are generally understudied and under-collected due to a combination of small population sizes, occurrence in restricted locations. Aquatic plants are additionally overlooked because they are more difficult to access; thus, collection efforts are typically biased towards terrestrial species. These understudied cornerstone species in an overlooked biodiversity hotspot provide an excellent opportunity to advance our understanding of the sources and patterns of endemic diversity in the NACP. The pondweed family (Potamogetonaceae) is one of the most species-rich freshwater aquatic plant families in the world and contributes greatly to the submersed aquatic plant diversity in the northern hemisphere. Despite their dominance in freshwater ecosystems and ecological and economical importance in maintaining these systems, there is a lack of basic biological knowledge for these plants. One of the most basic barriers to further research is poor taxonomic resolution. Potamogeton has historically been one of the most difficult aquatic plant groups to describe and the genus is known to readily hybridize. It is estimated that there are as many if not more hybrids than distinct species. Hybrid species are often excluded from biodiversity assessments, either passively or explicitly. Given that hybrids greatly contribute to taxonomic diversity and taxonomic confusion, more robust identification of hybrid species and their evolutionary origins will help resolve pondweed taxonomy and provide a more accurate assessment of biodiversity in the NACP. Geological processes that fragment species distributions, such as glaciation cycles and sea level fluctuations, can facilitate speciation by reproductively isolating populations for thousands to millions of years. These processes can also bring together species that did not previously share a geographic range. In the case of Potamogeton, in which species readily hybridize where they co-occur, such events likely promoted diversification through both population fragmentation and new combinations of co-occurring species. Currently, P. floridanus is the only hybrid species recognized in the southeastern US, which seems to be more an artifact of collection bias than a biological reality. This study aims to (1) assess the factors contributing to hybridization in Potamogetonaceae, (2) resolve confusion regarding the taxonomy and phylogentic relationships within Potamogetonaceae, (3) identify other potential Potamogetonaceae hybridization events within the NACP.