Yellow iris (Iris pseudacorus)

A patch of iris with yellow flowers growing in a wetland.

 
 

Yellow iris is a perennial plant that grows in wet areas and along shorelines. It can form dense patches and crowd out native vegetation.

Warning: Wear gloves and cover your skin if working with the plant as contact with the plant and its sap can cause skin irritation.

Description

Appearance

Yellow iris is a perennial, herbaceous, aquatic plant whose leaves and flowers grow above the water surface. It grows 2-3 feet tall along shorelines in shallow water and has showy yellow flowers.

Leaves and Stem

Leaves are broad, flat, sword-shaped, stalkless, and have parallel veins. The leaves embrace the flower stalk.

Flowers

Flowers are deep yellow with two or three on one stalk. The flower stalk is round and shorter than the outer leaves. The flowers have three outer drooping sepals, which are yellow with brownish mottled markings, surrounding the true flower, which is also yellow. Flowers bloom from May through July.

Fruit and Seeds

The fruit is a capsule containing dozens of smooth, flattened seeds that look like thick coins.

Rhizomes and Roots

Yellow iris reproduces vegetatively through horizontal stems growing below the soil surface, called rhizomes, forming roots and producing new plants.

Biology

Yellow iris is a perennial plant that grows in two to three of water. It can reproduce by seed and also spread vegetatively.

Origin and Spread

Yellow iris is native to Eurasia. It was introduced as an ornamental plant. It has spread from being planted along shorelines and wet areas. Seeds can spread in water.

Refer to EDDMapS Distribution Maps for current distribution.

Don't be fooled by these look-alikes

  • Northern blue flag iris, Iris versicolor (native) - Common native plant along Minnesota water bodies. Northern blue flag iris has purple flowers. It is difficult to distinguish from yellow iris when flowers are not present.
  • Bearded iris with yellow flowers, Iris germanica (non-native) - Bearded iris are the most commonly seen cultivated iris planted as ornamentals around homes and gardens. Horticulturalists have bred many cultivars of bearded iris and they come in many flower colors including yellow. Bearded iris generally do not grow in wet areas. Bearded iris have a "beard" on the flower sepal—it looks like a fuzzy caterpillar on the showy sepals.
 
Regulatory Classification

Yellow iris (Iris pseudacorus) is a Minnesota Department of Natural Resources regulated invasive species in Minnesota. It is legal to possess, sell, buy, and transport regulated invasive species, but they may not be introduced into a free-living state, such as being released or planted in public waters. It should not be used for shoreline planting along public waters because the plant can effectively spread to other areas of the water body by rhizomes and seed movement during times of high water.

Threat to Minnesota
  • Yellow iris competes with native shoreline vegetation.
  • It can form dense mats that can narrow waterways.
  • All parts of the plant are toxic to livestock and other animals.
What you should do

One way that invasive plant seeds and fragments can spread is in soil.  Sometimes plants are planted purposefully.  You can prevent the spread of invasive plants.

PlayCleanGo: Stop Invasive Species in Your Tracks

  • REMOVE plants, animals & mud from boots, gear, pets & vehicle.
  • CLEAN your gear before entering & leaving the recreation site.
  • STAY on designated roads & trails.
  • PLANT non-invasive species.
Native Substitutes
 
Control Methods

Mechanical control can be done by digging out the plant. Care must be taken to dig out the rhizomes (roots) as the plant can grow from fragments of rhizomes. A permit is required to manage plants in public waters. Wear gloves and cover your skin if working with the plant as contact with the plant and its sap can cause skin irritation.

Herbicide controlcan be done using a glyphosate herbicide labeled for use in water (Rodeo, for example). A permit is required to manage plants in public waters.

Reporting

Report new occurrences by submitting a report through EDDMapS Midwest or by emailing your regional aquatic invasive species specialist.

Resources