Yellow Flag Iris (photo by Kenn Stearns)

The Yellow Flag Iris (Iris pseudacorus ) is an invasive non-native plant. This herbaceous perennial colonizes in large numbers forming dense monotypic stands that serve as impenetrable mats that clog small streams, choke pipes, and crowd out desirable wetland plant species, including those that are an important food source for wildlife. Connecticut, Massachusetts, Montana, New Hampshire, Oregon, Vermont, and Washington have listed the Yellow Flag Iris as a state noxious weed.

Plant species become invasive when they are introduced to an area outside their native range and are free from natural competitors and predators, allowing them to proliferate and persist to the detriment of native species. Second only to direct habitat destruction, invasive non-native species such as the Yellow Flag Iris are the second greatest worldwide threat to native species and ecosystems. Invasive non-native plants can…

• displace native species,
• disrupt ecosystem relationships,
• degrade wildlife habitat,
• impede recreation,
• cause economic damage to forests, agricultural crops and other managed lands
• cost the American public an estimated $138 billion each year
• negatively impact about 42% of the plant and animal species listed by the Federal government as threatened or endangered