yellow-flag iris

Yellow Flag Iris

Scientific name: Iris pseudacorus

Common name: Yellow-flag iris

Description: Yellow-flag iris is a perennial wetland plant originally from Eurasia and sometimes used as a garden ornamental. In the summer, dense stands of yellow-flag become evident due to a show of abundant yellow flowers. After flowering, it develops 3-inch long seed capsules, and it’s seeds spread by floating throughout waterways. When not in flower, yellow-flag can often be confused with native cattails due to both having flat, pointed leaves and growing in similar habitats.

Impact: Yellow-flag iris is able to take over shorelines, wetlands, and river banks by out-competing native plants. In turn, dense stands of yellow-flag create less favorable habitat for native salmon and other wildlife. Where present, it can act to fill in small waterways, negatively impact irrigation systems, cause intestinal problems in cattle, cause skin dermatitis in humans, and it’s seeds can clog pipes. The ability to spread both by water borne seeds and severed rhizomes makes yellow-flag especially difficult to contain. If you suspect yellow-flag iris is on your property, please contact our office at 503-325-4571.

Source: KingCounty.gov

For more information, please visit the Noxious Weed resources at KingCounty.gov: http://your.kingcounty.gov/dnrp/library/water-and-land/weeds/BMPs/yellow-flag-iris-control.pdf