yellowflag iris

Liliales > Iridaceae > Iris pseudacorus L.
Synonym(s): paleyellow iris

Yellowflag iris is a perennial plant that occurs in wet areas such as ditches and marshes. Leaves arise from the base of the plant and are flattened, 3-4 ft. (0.9-1.2 m) long with a raised mid-rib. Bright yellow flowers appear in late spring to early summer. Flowers develop in groups of 2-10 and have three drooping, yellow sepals with purple-brown markings and 3 smaller, unmarked and upright yellow petals. Flowers are about 3 in. (7.6 cm) wide. Fruit are brown capsules that are 2 in. (5 cm) long. Yellowflag iris was introduced into the United States in the mid-1800s as an ornamental from Eurasia or Northern Africa. Plants can withstand a wide variety of conditions, including brackish water, acidic water and periods of drought.


Identification, Biology, Control and Management Resources

  • Weeds of the Week - USDA Forest Service, Northeastern Area, Forest Health Protection

Selected Images from Invasive.org

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Plant(s); along drainage area
Nancy Loewenstein, Auburn University, Bugwood.org
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Root(s); Inside of cut rhizome
Leslie J. Mehrhoff, University of Connecticut, Bugwood.org
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Flower(s); pale yellow form
Leslie J. Mehrhoff, University of Connecticut, Bugwood.org
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Flower(s);
Nancy Loewenstein, Auburn University, Bugwood.org
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Flower(s);
Nancy Loewenstein, Auburn University, Bugwood.org
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Flower(s);
Nancy Loewenstein, Auburn University, Bugwood.org
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Fruit(s);
Leslie J. Mehrhoff, University of Connecticut, Bugwood.org
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Infestation;
Leslie J. Mehrhoff, University of Connecticut, Bugwood.org
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Plant(s); along drainage area
Nancy Loewenstein, Auburn University, Bugwood.org
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Plant(s); in flower
Todd Pfeiffer, Klamath County Weed Control, Bugwood.org
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Seed(s);
Steve Hurst, USDA NRCS PLANTS Database, Bugwood.org
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Diagram or Graphic; USDA NRCS. Wetland flora: Field office illustrated guide to plant species. USDA Natural Resources Conservation Service.
USDA PLANTS Database, USDA NRCS PLANTS Database, Bugwood.org
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Diagram or Graphic; Britton, N.L., and A. Brown. 1913. Illustrated flora of the northern states and Canada. Vol. 1: 540.
USDA PLANTS Database, USDA NRCS PLANTS Database, Bugwood.org
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Invasive Reference(s):

Check Invasive.org for most current lists.
  • California - Invasive Plant Inventory
  • Connecticut - Noxious Weed Law
  • Massachusetts - Noxious Weed Law
  • Montana - Noxious Weed Law
  • New Hampshire - Noxious Weed Law
  • Oregon - Noxious Weed Law
  • Rhode Island - Noxious Weed Law
  • Tennessee - EPPC List
  • Texas - Invasive Plant List
  • Virginia - Invasive Alien Plant Species
  • Washington - Noxious Weed Law
  • Mid-Atlantic - EPPC List
  • Invasive Plants: Guide to Identification and the Impacts and Control of Common North American Species
  • Invasive Plants of the Upper Midwest
  • Invasive Plant Atlas of New England


External Links


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USDA Forest Service Bugwood University of Georgia