Ten years later, purple loosestrife had displaced native food and cover plants in the waterway surrounding the green-tree impoundment at the Montezuma Refuge.
Biologist holding stadia rod in middle foreground is obscured by mature plants.
By the late 1800's it had spread throughout the northeastern United States and southeastern Canada, reaching as far north and west as Manitoba. L. salicaria caused few problems until the 1930's when it became aggressive in the floodplain pastures of the St. Lawrence River. Since then, it has steadily expanded its local distribution and now poses a serious threat to native emergent vegetation in shallowwater marshes throughout the northeastern and northcentral regions. Recent records indicate that purple loosestrife is also tolerant of soils and climates beyond these regions and threatens to become a serious problem in wetlands and irrigation systems in the Great Plains and the Far West. U.S. Fish and Wildlife Service.