"Purple loosestrife (Lythrum salicaria), a beautiful but aggressive invader, arrived in eastern North America in the early 1800’s. Plants were brought to North America by settlers for their flower gardens, and seeds were present in the ballast holds of European ships that used soil to weigh down the vessels for stability on the ocean. Since it was introduced, purple loosestrife has spread westward and can be found across much of Canada and the United States...Garden varieties of loosestrife, which were once thought to be sterile, have been proven to cross pollinate with wild purple loosestrife to produce viable seed." (MN Sea Grant) Lythrum virgatum 'Morden Gleam' was developed by crossing L. virgatum ‘Morden Pink’ with select forms of the North American native L. alatum. This cultivar is now prohibited in several states.