Alnus maritima (also called Seaside Alder) is a species of plant in the Betulaceae family. Alnus maritima is endemic to the United States, and is found naturally in three disjunct populations in Oklahoma, Georgia, and in Maryland and Delaware on the Delmarva Peninsula. In 2002, the three populations were recognized as subspecies and given the names Alnus maritima subsp. oklahomensis, Alnus maritima subsp. georgiensis, and Alnus maritima subsp. maritima, respectively. While some believe that subspecies maritima is the oldest of the three subspecies and that the other two disjunct populations resulted from some form of long distance dispersal, evidence from morphometric and phylogeographic studies indicates that the Oklahoma population (subsp. oklahomensis) is in fact the most ancestral and