Page authors: Don Knoke, David Giblin
Iris pseudacorus
pale yellow iris

Distribution: Occurring on both sides of the Cascades crest in Washington, but more common west of the crest; British Columbia to California, east to Idaho and Montana; also in eastern North America.

Habitat: Wetlands, lake and pond margins, irrigation ditches, backwaters, and other wet places where often disturbed; invasive.

Flowers: May-July

Origin: Introduced from Eurasia

Growth Duration: Perennial

Conservation Status: Not of concern

Pollination: Bumblebees, bees, flies, hummingbirds


Herbaceous perennial from short, thick rhizomes, forming dense clumps, the simple flowering stem up to 1 m. tall, leafy.


Basal leaves stiff, narrowly linear, 5-9 dm. long and 10-15 mm. broad; cauline leaves reduced upward.


Inflorescence branched, few to several flowered, 1.5-5 dm. long; flowers pale to deep yellow, purple-lined; pedicles up to 5 cm. long; perianth parts fused in a tube at the base, the tube about about 12 mm. long; sepals 3, obovate, spreading, about 5 cm. long; petals 3, much shorter and narrower than the sepals, upright; stamens 3, opposite the sepals; style branches 3, about 22 mm. long, with 2 terminal lobes less than as long; stigma triangular; ovary inferior.


Capsule 3-celled, leathery, 5-8 cm. long.

Accepted Name:
Iris pseudacorus L.
Publication: Sp. Pl. 1: 38. 1753.

Synonyms & Misapplications:
(none provided)
Additional Resources:

PNW Herbaria: Specimen records of Iris pseudacorus in the Consortium of Pacific Northwest Herbaria database

WA Flora Checklist: Iris pseudacorus checklist entry

OregonFlora: Iris pseudacorus information

E-Flora BC: Iris pseudacorus atlas page

CalPhotos: Iris pseudacorus photos

39 photographs:
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