Iris missouriensis
Western blue flag, Western Blue Flag
(c) Adam J. Searcy, some rights reserved (CC BY) · licence
Family: Iridaceae · Type: Herb · Native
Iris missouriensis (Western blue flag) is a native California herb in the Iridaceae family, recognized by high elevation wetland habitat diagnostic.
Western blue flag is a California native perennial found in the Klamath Ranges, northern Coast Ranges, Sierra Nevada, southern Coast Ranges, Transverse Ranges, Peninsular Ranges, and Great Basin in vernally moist grassy or rocky areas at elevations of 900 to 3,400 meters. Flowering from May to July, this plant produces pale lilac to nearly white flowers with lilac-purple veining, 4 to 7 centimeters long with broad, widely oblanceolate petals. Growing with rarely branched stems 20 to 50 centimeters tall from a thick rhizome 20 to 30 millimeters in diameter, it emerges from underground root structures. Its basal leaves are 3 to 9 millimeters wide, with the base sometimes tinged purple, and cauline leaves reduced to bract-like structures along most of the stem length. The flowers feature large sepals 4 to 7 centimeters long and 18 to 22 millimeters wide, with distinctive style branches 25 to 35 millimeters long.
Identification and appearance
Key characters: 19 sympatric species; high elevation wetland habitat diagnostic
Habitat and range
Habitat: Vernally moist grassy or rocky areas
Elevation: 900-3400 m
California counties: Mono, Inyo, San Bernardino, Siskiyou, San Benito, Ventura, Kern, San Diego, Modoc, San Francisco, San Mateo, Monterey, Lassen, Sonoma, Mendocino, Plumas, Marin, Solano, Santa Clara, Shasta, Humboldt, Butte, Madera, Mariposa, Tulare, Nevada, El Dorado, Fresno, Sierra, Glenn, Colusa, Tuolumne, Lake, Del Norte, Alpine
Outside California: western North America, northern Mexico
Bloom period
Iris missouriensis blooms May-Jul.
How to tell it apart
vs Dietes: Iris has broad petal-like style branches; Dietes has thread-like styles and flowers lasting only one day.; vs Canna: Iris has six-parted flowers with drooping sepals; Canna has asymmetric flowers with one petal-like stamen.; vs Hemerocallis: Iris has petal-like style branches opposite stamens; Hemerocallis has simple thread-like styles and six equal tepals.; vs Typha: Iris has showy six-parted flowers; Typha has dense brown cylindrical flower spikes (cattails).; vs Sisyrinchium: Iris has large flowers with drooping outer sepals; Sisyrinchium has small flat flowers with six equal tepals.
Frequently asked questions
Is Iris missouriensis native to California?
Yes. Iris missouriensis is native to California (recorded as native).
When does Iris missouriensis bloom?
Iris missouriensis blooms May-Jul.
Where in California does Iris missouriensis grow?
Iris missouriensis occurs in Mono, Inyo, San Bernardino, Siskiyou, San Benito, Ventura, Kern, San Diego and other counties, at elevations of 900-3400 m.
What plant family does Iris missouriensis belong to?
Iris missouriensis is in the Iridaceae family, genus Iris.
What habitat does Iris missouriensis grow in?
Iris missouriensis grows in Vernally moist grassy or rocky areas.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · Index of California Plant Names · CalPhotos
Last updated 2026-10-07
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.