Yellow iris

Scientific Name: Iris pseudacorus

Pam Fuller - USGSCopyright Info

Identification: Yellow iris is a perennial plant with elongated, dark green leaves and bright yellow flowers. It grows in clusters connected by pink, horizontal stems. Each flowering stem may carry several flowers that bloom from April to June, depending on latitude. This species is also known as yellow flag or water flag.

Size: Yellow iris typically grows to 3-5 feet (1-1.5 m) tall, with leaves 3 feet (90 cm) long and flowers 3-4 inches (7-10 cm) across.

Native Range: This species is native to Eurasia.

Table 1. Great Lakes region nonindigenous occurrences, the earliest and latest observations in each state/province, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Iris pseudacorus are found here.

Full list of USGS occurrences

State/ProvinceYear of earliest observationYear of last observationTotal HUCs with observations†HUCs with observations†
Indiana198220181Little Calumet-Galien
Michigan1932201940Au Gres-Rifle; Au Sable; Betsie-Platte; Black-Macatawa; Boardman-Charlevoix; Brule; Carp-Pine; Cheboygan; Clinton; Detroit; Flint; Great Lakes Region; Huron; Kalamazoo; Kawkawlin-Pine; Lake Erie; Lake Huron; Lake Michigan; Lake St. Clair; Little Calumet-Galien; Lower Grand; Manistee; Manistique; Maple; Michigamme; Muskegon; Ontonagon; Ottawa-Stony; Pere Marquette-White; Pigeon-Wiscoggin; Raisin; Saginaw; Saginaw; Shiawassee; Southeastern Lake Michigan; St. Joseph; Tahquamenon; Thunder Bay; Tittabawassee; Upper Grand
Minnesota200820173Beaver-Lester; Cloquet; St. Louis
New York188620189Black; Great Lakes Region; Oak Orchard-Twelvemile; Oneida; Oswego; Seneca; Southwestern Lake Ontario; St. Lawrence; Upper Genesee
Ohio201320131Lake Erie
Pennsylvania195420131Lake Erie
Vermont190920075Lake Champlain; Missiquoi River; Otter Creek; St. Francois River; Winooski River
Wisconsin2005201816Bad-Montreal; Beartrap-Nemadji; Black-Presque Isle; Door-Kewaunee; Lake Michigan; Lake Superior; Lower Fox; Manitowoc-Sheboygan; Milwaukee; Northwestern Lake Michigan; Oconto; Peshtigo; Southwestern Lake Michigan; St. Louis; Upper Fox; Wolf

Table last updated 10/12/2019

† Populations may not be currently present.

Means of Introduction: This plant is widely sold as an ornamental landscape plant. It is planted for its showy yellow flowers and for its erect, sword-like leaves. It often spreads locally along shorelines, streams, and into fresh and somewhat salty marshes.

Status: Yellow iris is widespread in the northeastern United States, where it has been found in the wild for nearly 140 years. Although recorded in more than 40 states, yellow iris is not equally distributed or problematic throughout the United States.

Remarks: Burning and mechanical removal of yellow iris are not recommended for control. This plant has a tendency to re-grow from old stems, and summer fires do not suppress seedling growth in spring. Mechanical removal in sensitive areas, such as shallow streambeds, can disturb the waterbody floor and allow the establishment of other unwanted plants. Therefore, the best method for controlling yellow iris may be cutting, followed by herbicide treatment.

There are many yellow-flowered upland iris species that are non-problematic.

Author: Illinois-Indiana Sea Grant

Contributing Agencies:
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Revision Date: 9/25/2012

Citation for this information:
Illinois-Indiana Sea Grant, 2019, Yellow iris: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, and NOAA Great Lakes Aquatic Nonindigenous Species Information System, Ann Arbor, MI,, Revision Date: 9/25/2012, Access Date: 10/13/2019

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.