A total of 99 species of trees have been documented from the George Washington Memorial Parkway (GWMP). These include 14 species of non-native trees. Shrubs are represented by 92 species, 25 of which are non-native species. The most common genus of tree or shrub is Quercus (oaks) which are represented by 15 species. Five of the trees or shrubs known from GWMP are listed by the States of Virginia or Maryland as rare, threatened or endangered.