Flower profile

Yellow iris

Iris pseudacorus

Yellow iris (Iris pseudacorus) is a flowering plant in the Iridaceae family, introduced in the lower 48 states, blooming mostly April–June across the U.S.

Not native to Washington

Yellow iris is a wildflower that USDA PLANTS lists as introduced in the lower 48 states. In Washington it's most often seen in bloom in May–June.

40states where USDA records it

2,035WA sightings*

21,618U.S. sightings*

*iNaturalist research-grade observations, as of October 17, 2026.

On our lists for: Washington

🚫

Regulated invasive plant in Washington. It's on that state' official invasive plant list (Washington: Class C noxious weed). Please don't plant or share it there. ^{WAC 16-750}

Quick look

Iris pseudacorus, the yellow flag, yellow iris, or water flag, is a species of flowering plant in the family Iridaceae. It is native to Europe, western Asia and northwest Africa. Its specific epithet pseudacorus means "false acorus", referring to the similarity of its leaves to those of Acorus calamus, as they have a prominently veined mid-rib and sword-like shape. However, the two plants are not closely related.
From Wikipedia's article Iris pseudacorus, CC BY-SA 4.0.

It belongs to the Iridaceae family. ^iNaturalist
USDA PLANTS describes it as an herb (forb) with a perennial life cycle. ^{USDA PLANTS}
USDA PLANTS lists it as introduced in the lower 48 states and records it in 40 states. ^{USDA PLANTS}
NatureServe lists it as not native to Washington. ^NatureServe
In Washington, most iNaturalist sightings of it in flower come in May–June. ^iNaturalist
iNaturalist has 2,035 research-grade sightings of it in Washington, ranking #92 among the 187 flowers on our Washington list. ^iNaturalist

When does it bloom?

In Washington, most flowering sightings come in May–June.

Flowering records by month in Washington (iNaturalist research-grade observations marked “Flowering”) (274 records)

Conservation status

Federal (U.S. ESA): Not listed No U.S. Endangered Species Act listing in the USFWS ECOS database. ^{USFWS ECOS}
NatureServe global: GNR Not yet ranked worldwide. ^NatureServe
Washington: No list Washington has no state law listing endangered or threatened plants (the Washington Natural Heritage Program's rare plant list isn't regulatory), so we show NatureServe's Washington ranks instead. NatureServe: SNA, not applicable (usually because it isn't native there) in Washington.
Rare elsewhere: No other U.S. state ranks it S1, S2, SH or SX.

Checked October 17, 2026. Rankings and lists can change, so follow the links for the latest.

Can you eat it?

For peoplePoisonous to people

NC State Extension lists it as poisonous to humans (severity: low). Symptoms they list: “Salivation, vomiting, drooling, lethargy, diarrhea. Highest concentration in rhizomes” ^{NC State Extension}

For petsToxic to dogs, cats and horses

ASPCA's entry “Flag” (Iris species), which covers the whole genus, lists it as toxic to dogs, cats and horses. Signs include: Salivation, vomiting, drooling,lethargy, diarrhea. Highest concentration in… ^ASPCA

🌿 Never eat a wild plant unless you're certain of its ID; this isn't medical advice. Worried about a person? Call Poison Control at 1-800-222-1222. Worried about a pet? Call your vet.

Where does it grow?

USDA PLANTS records yellow iris in 40 states plus Washington, D.C.

AKMEVTNHWAIDMTNDMNILWIMINYRIMAORNVWYSDIAINOHPANJCTCAUTCONEMOKYWVVAMDDEAZNMKSARTNNCSCDCOKLAMSALGAHITXFL

recorded by USDA PLANTS on our state lists not recorded

See the full list of states

Alabama, Arkansas, California, Connecticut, Delaware, Florida, Georgia, Idaho, Illinois, Indiana, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New York, North Carolina, Ohio, Oregon, Pennsylvania, Rhode Island, South Carolina, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin; District of Columbia.

Washington counties with USDA records: Chelan, Clallam, Cowlitz, Ferry, Grant, Grays Harbor, Island, Jefferson, King, Kitsap, Kittitas, Lewis, Mason, Pacific, Pend Oreille, Pierce, San Juan, Skagit, Snohomish, Stevens, Thurston, Wahkiakum, Walla Walla, Whatcom.

Names, range and relatives

Native status by region (USDA PLANTS): Canada: Introduced; Lower 48 states: Introduced.

County records: USDA PLANTS lists it in 311 counties across 36 states; the most are in Virginia (33), New York (28), Pennsylvania (24).

Other Iris on Bloomipedia (11): Irises, Dwarf crested iris, Douglas iris, Western blue flag, Northern blue flag iris, Southern blue flag, Oregon iris, Dwarf iris, Beach-head iris, Dwarf lake iris.

More from the Iridaceae family (14 on Bloomipedia; most observed first): Western blue-eyed grass, Blue pigroot, Grasswidow.

More Washington flowers

Grasswidow

Olsynium douglasii

Native

🌼 Blooms in WA: February–April

Salmonberry

Rubus spectabilis

Native

🌼 Blooms in WA: March–May

Salal

Gaultheria shallon

Native

🌼 Blooms in WA: May–July

Sources

USDA, NRCS. PLANTS Database, profile IRPS.
iNaturalist, Iris pseudacorus: taxonomy, research-grade observation counts and “Flowering” annotations, retrieved October 17, 2026.
Wikipedia, Iris pseudacorus (lead quoted under CC BY-SA 4.0).
Washington: Washington State noxious weed list (WAC 16-750-005, -011, -015).
USFWS, ECOS species database (ESA listing check), October 17, 2026.
NatureServe Explorer, Iris pseudacorus (global and state ranks).
Edibility and toxicity: NC State Extension; ASPCA.
Photo: Juan C. Espinosa via iNaturalist · CC BY 4.0 · resized.