Iris missouriensis Nutt.
western blue iris (Rocky Mountain iris)
Iridaceae (Iris family)

Introduction to Vascular Plants


© Thayne Tuason     (Photo ID #76371)


E-Flora BC Static Map

Distribution of Iris missouriensis
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Species Information

Perennial herb from a thick rhizome; flowering stems usually simple, sometimes branched, 20-50 cm tall.
Mostly basal, linear-lanceolate, 20-50 cm long, 5-10 mm wide, entire, the tips long-pointed.
Inflorescence of 1 or 2, sometimes 3 or 4, showy flowers on stout, 4- to 6-cm long stalks; flowers light to deep blue, purple-lined, the tubes flared above, less than 6 mm long, the bracts green or reddish and not papery at flowering; petals erect, 3-6 cm long, 1.5-2 cm wide; sepals oblanceolate, 5-6 cm long, about 1 cm wide, bent back; style branches 2-2.5 cm long, the crests less than 1/2 as long; stigmas 2-lobed.
Capsules, cylindrical, 3-5 cm long; seeds numerous.

SourceThe Illustrated Flora of British Columbia


If more than one illustration is available for a species (e.g., separate illustrations were provided for two subspecies) then links to the separate images will be provided below. Note that individual subspecies or varietal illustrations are not always available.

USDA Species Characteristics

Flower Colour:
Blooming Period:
Fruit/Seed characteristics:
Colour: Black
Present from Summer to Spring
Source:  The USDA

Habitat and Range

Moist lake margins and marshy meadows in the lowland and montane zones; rare in W BC, known from scattered localities, where probably introduced; E to SE AB and S to MN, NE, NM, AZ, CA and N MX.

SourceThe Illustrated Flora of British Columbia


Synonyms and Alternate Names:
Iris longipetala Herbert
Iris missouriensis var. arizonica (Dykes) R.C. Foster
Iris missouriensis var. pelogonus (Goodding) R.C. Foster
Iris pariensis S.L. Welsh
Iris tolmieana Herbert