Pale Yellow Iris (Iris pseudacorus)

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Clumping perennial plant forms dense stands of robust plants with stout rhizomes. Leaves erect with upper part arching; leaves flattened, arising in a fan from the soil; raised midrib; sword-like, fine-pointed; 1-1.25 m in height. Flowers on erect stalks; large, showy, pale to deep yellow; several flowers on each stem; flowers having 6 clawed perianth segments including 3 large downward-spreading sepals and 3 smaller erect petals; on each flower sepal (yellow, large and petal-looking) are patterns of delicate light-brownish to purple veins or flecks. Fruit a capsule (seed pod); large 4-8 cm, 3-angled cylindrical, glossy green; many flattened brown seeds. Warning: The leaves, and especially the rhizomes, of this species contain an irritating resinous substance called irisin. If ingested this can cause severe gastric disturbances. Plants can cause skin irritations and allergies in some people.

Key Identifiers
  • sword like leaves
  • showy yellow flower are 8-10 cm across
  • showy tongue-shaped sepals are often adorned with brown spots or purple vein
  • plant has a long blooming season
Location in Canada
It escaped cultivation, and is now documented as established in Canada from British Columbia, Saskatchewan, Alberta, Manitoba, Ontario, Quebec, Newfoundland, New Brunswick and Nova Scotia.

Nicole Kimmel, ARD

Nicole Kimmel, ARD
Resources Similar species
Iris pseudacorus especially when not in bloom might be confused with:
  • Common Cattail (Typha latifolia) - Leaves are very similar, but lacks the showy yellow flowers.
  • Narrow-leaved Cattail (Typha angustifolia) - Leaves much narrower, and lacks the showy yellow flowers.
  • Rocky Mountain Iris (Iris missouriensis) - Much smaller plant and has blue flowers.
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Other Documents in the Series

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This document is maintained by Shelley Barkley.
This information published to the web on April 11, 2012.
Last Reviewed/Revised on August 21, 2018.