Page authors: Don Knoke, David Giblin
Iris tenax
Oregon flag, tough-leaf iris

Distribution: Occurring west of the Cascades crest in Washington; Washington to California.

Habitat: Prairies, meadows, open oak and coniferous forests, at low to middle elevations.

Flowers: April-June

Origin: Native

Conservation Status: Not of concern


Herbaceous perennials from slender rhizomes, forming large clumps, the slender flowering stems up to 3.5 dm. tall with 1-4 leaves.


Leaves mostly basal, narrowly linear, up to 4 dm. long and 2-6 mm. broad; cauline leave few, reduced upward.


Flowers usually solitary, lavender or blue to purple, but occasionally white to yellow or pinkish, subtended by a pair of involucral leaves which may be 2 cm. apart; pedicels 1-4 cm. long; perianth parts fused in a tube at the base, the tube 6-10 mm. long; sepals 3, oblanceolate to obovate, 5.5-6.5 cm. long, spreading; petals 3, oblanceolate, 3.5-6 cm. long, erect; style branches 25-30 mm. long with 2 terminal lobes 8-12 mm. long; stigmas triangular; ovary inferior.


Capsule 3-celled, leathery, 25-35 mm. long.

Accepted Name:
Iris tenax Douglas ex Lindl.
Publication: Edwards’s Bot. Reg. 15: plate 1218. 1829.

Synonyms & Misapplications:
(none provided)
var. tenax – Oregon flag, tough-leaf iris    Occurring west of the Cascades crest in Washington; Washington to California. Washington to California.
Additional Resources:

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

WA Flora Checklist: Iris tenax checklist entry.

E-Flora BC: Iris tenax atlas page.

CalPhotos: Iris tenax photos.

USDA Plants: Iris tenax information.

20 photographs:
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