The distributions of native North American hydrophytes, other than those of widespread range, are correlated here with the eastern and midwestern physiographic regions of the continent. These regions reflect the present-day topography of the landscape that has resulted from the past geological, climatological, glacial, and floristic history. From the time of the origin of the angiosperms, the oldest regions available for their occupancy in eastern North America were the southern Appalachian Upland and the Interior Highlands or Ozark-Ouachita Plateau. These large areas have been available for plant occupancy since the retreat of the continental Cretaceous seas and the withdrawal of the Wisconsinan glacial ice sheet. Those hydrophytes that originated or invaded the southern Appalachian Upland or the Interior Highlands, have had the oppurtunity to spread in various directions and at different times as the result of geological and historical events on the continent. The following migrations of hydrophytes must have occured from the Southern Appalachian Upland and/or the Interior Highlands: (1) invasion of the Atlantic and Gulf Coastal Plains that became available following withdrawal of the Cretaceous seas and later following the retreat of the Eocene and Miocene waters during the Tertiary; (2) invasion of the largest region, the northern US and Canada, that became available for extensive occupation of plants following the retreat of the Wisconsinan glacier. The invasion of non-indigenous (foreign, alien) species has occurred since the mid-eighteenth century by the migration and settlement of European people on the North American continent. These invasive species can be recognized into six broad distribution patterns: (1) widespread; (2) northern US and Canada and western US and British Columbia; (3) northeastern US and eastern Canada; (4) southeastern US and pacific Coastal States; (5) southeastern US; (6) Coastal Pacific States of the US. In North America, aquatic and wetland species, both native and foreign, may have parallel distributions. Native species are expanding and contracting conforming to distributional patterns already The invasions of foreign species through time develop distributions that also come to conform to ranges and patterns similar to those of native species. For example, similar distributional ranges are evident with both native and non-native species that occupy the Coastal Plains of the eastern southern US, the northeastern US and southeastern Canada, and inland to include the Great lakes region and even farther western, and also in the individual states of California and Florida The distribution patterns of present-day aquatic and wetland angiosperms, at the continental or worldwide scope, are primarily the result f two major disturbances on the earth surface: (1) the natural disturbance from Pleistocene Glaciation in the Northern Hemisphere, and (2) the artificial disturbance from agricultural, industrial, and recreational activities of human beings throughout the entire world.