Native to Europe, western Asia and northwest Africa, this herbaceous plant has become invasive in wetlands in the central and eastern United States. The flowers are bright yellow, with the typical iris form. Although it is a welcome sight in its native range, in the U.S. it has escaped from cultivation to establish itself as an invasive aquatic plant which can create dense, monotypic stands, outcompeting other plants in the ecosystem. It is difficult to remove due to its rhizomes and easy to spread due to water-dispersed seeds. A native alternative in the U.S would be Blue Flag Iris (Iris virginica).
