Department Header For Noxious Weed Division
Yellowstone County, Montana
Noxious Weed
Weed Information Contact Department

Yellowflag Iris
(Iris pseudacorus)


Yellowflag Iris

Photos from Montana's Noxious Weeds, revised ed.
by Monica Pokorny & Roger Sheley.

Used with permission from
Montana State University Extension.

Yellowflag Iris Toxic

Yellowflag Iris Stem

Yellowflag Iris Infestation

Yellowflag Iris Flower

Yellowflag Iris Seeds

Yellowflag Iris Root

Photos from Montana Weed Control Association


Toxicity: Toxic. Livestock, dogs, cats and humans.

Growth Habit: herbaceous perennial found in wet areas in water up to 10 inches deep. Plants are 3 to 4 feet tall with long, linear, dark green leaves.

Leaves: long, linear, dark green leaves, leaves emerge from the ground in fan-like arrangement. Similar to a common garden iris. Leaves have a raised midrib and are erect with the upper part arching.

Stem: stems consist of flower stalks.

Flower: several flowers are born on erect flower stalks.

Roots: rhizomes


Reproduction: can spread by rhizomes and seeds.

Habitat: Wetlands and riparian areas.

Biological Controls:

Herbicides: Glyphosate

Video Supplied By Montana Weed Control Association