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Yellow flag iris (Iris pseudacorus)

Yellow flag iris Common Names: Paleyellow iris

Description: Its six-angled capsule distinguishes it from blue flag (three-angled capsule) later in the season.

Habit: Herbaceous perennial, ranging from 0.5-1 m (1.5-3 ft) in height, erect, perennial, semi-aquatic, stems usually shorter than the leaves, roots densely crowded rhizomes.

Leaves: Narrow, stiff, erect, sword-like.

Stems: Shorter than leaves; erect.

Flowers: Yellow in color, 3 downward-spreading petal-like sepals; 3 upward-pointing petals; sepals often with irregular dark markings; blooms May through June.

Fruit and seeds: Seed pod, 3-celled, leathery, 5-8 cm. long.

Habitat: Native to Europe. Found along edges of lakes, ponds, rivers, streams and floodplain forest; grows in water depths of up to 25 cm (10 in).

Reproduction: By floating seed, vegetatively by rhizomes; dispersed by water and gardeners.

Similar species: Blue Flag (Iris versicolor) has a 3-angled capsule making it easier to distinguish once flowers die.

Monitoring and rapid response: Hand-pulling; cutting or mulching; effectively controlled by any of the several readily available general use herbicides such as glyphosate.

Credits: The information provided in this factsheet was gathered from the Michigan Natural Features Inventory and the University of British Columbia.

Individual species images that appear with a number in a black box are courtesy of the network ( photo author credits may not be included due to the small display size of the images and subsequent difficulty of reading the provided text. All other images appear courtesy of Google (

Common Name:

Yellow flag iris

Scientific Name:

Iris pseudacorus







USDA Symbol: