There are approximately 60 species of evening primrose that occur in the United States, about half o fall those in the world.  However, the only place in the world that the Antioch Dunes evening primrose can be found is on the Antioch Dunes.

The Antioch Dunes once comprised a unique dune ecosystem, with a multitude of plants and animals more characteristic of deserts of Southern California than of the surrounding Contra Costa County.  Located along the south bank of the San Joaquin River, this dune system averaged 800 feet in width and reached heights of 100 feet or more, stretching along the river for approximately two miles.  These dunes represented a biological "island" that harbored the northern extension of many desert plants and animals.

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