Yellow Flag Iris

Yellow Iris 1

Yellow Flag Iris (Iris pseudacorus)

The yellow iris is a robust plant with beautiful bright yellow flowers. The roots and bulbs are thick and fleshy, and the narrow sword-shaped leaves are bluish-green with a prominent mid-rib . Between 4 and 12 large, showy flowers are borne on a somewhat flattened stem ; they vary in colour from pale yellow to almost orange. An alternative name for this species is 'segg', which derives from an Anglo-Saxon word meaning 'short sword', and refers to the shape of the leaves . The fluttering of the flowers was thought to resemble flags blowing in the breeze, hence the name 'yellow flag'.


Leaves are erect with upper part arching; leaves flattened, arising in a fan from the soil; raised midrib; sword-like, fine-pointed; 3-4 feet in height

Yellow Iris 3


Flowers are on erect stalks (peduncles) 3-4 feet in height; bisexual; large, showy, pale to deep yellow; the only yellow iris in the U.S.; 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, (to 4 in.))
  • 3-angled cylindrical
  • Glossy green
  • Many flattened brown seeds


Common in wet habitats including wet meadows, wet woods, fens, wet, and the edges of watercourses, lakes and ponds it may also be found alongside coastal streams, on raised beaches, saltmarsh and shingle. It has in many cases been planted in the wild and escaped from gardens.

Please Contact Ravalli County Weed District if you've seen this plant!