Host an Event Volunteer Join Tickets

Support the plant database you love!


Plant Database

Search for native plants by scientific name, common name or family. If you are not sure what you are looking for, try the Combination Search or our Recommended Species lists.

Enter a Plant Name:
Or you can choose a plant family:
Iris missouriensis (Rocky mountain iris)
Smith, R.W.

Iris missouriensis

Iris missouriensis Nutt.

Rocky Mountain Iris, Western Blue Flag

Iridaceae (Iris Family)

Synonym(s): Iris longipetala, Iris missouriensis var. arizonica, Iris missouriensis var. pelogonus, Iris pariensis, Iris tolmieana


USDA Native Status: L48 (N), CAN (N)

Rocky Mountain iris is slender-stemmed and 1-2 ft. high. One to four flowers occur per stem. The grayish-green leaves are relatively broad. Large, delicate, pale blue to lavender to white flowers, often with purple veins, bloom at the top of stout, leafless (or with 1 short leaf) stalks that grow from dense clumps of flexible, tough, sword-shaped leaves.

This species often forms dense, large patches in low spots in pastures, where the tough leaves are avoided by cattle.


From the Image Gallery

43 photo(s) available in the Image Gallery

Plant Characteristics

Duration: Perennial
Habit: Herb
Fruit Type: Capsule
Size Notes: Up to about 2 feet tall.
Leaf: Green

Bloom Information

Bloom Color: White , Yellow , Blue , Purple
Bloom Time: May , Jun , Jul


USA: AZ , CA , CO , ID , MN , MT , ND , NE , NM , NV , OR , SD , UT , WA , WY
Canada: AB , BC
Native Distribution: B.C. to s. CA (mostly e. of the Cascades), e. to the Dakotas, NM & Mex.
Native Habitat: Marshes; wet meadows; drier areas if moist until flowering time

Growing Conditions

Water Use: High
Light Requirement: Sun
Soil Moisture: Wet
CaCO3 Tolerance: High
Soil Description: Wet soils.
Conditions Comments: This iris spreads to form colonies. It needs to be divided regularly.


Use Wildlife: Hummingbirds
Warning: POISONOUS PARTS: Rhizomes (thickened roots) and rootstocks, fresh or dry. Minor skin irritation when touched, low toxicity if ingested. Symptoms include nausea, vomiting, abdominal pain, diarrhea, elevated temperature following ingestion; skin irritation upon contact with seeds, rootstock, or cell sap. Toxic Principle: Irisin, iridin, or irisine. (Poisonous Plants of N.C.)

Conspicuous Flowers: yes
Attracts: Hummingbirds


Seed Collection: Easily collected from the large capsules.
Commercially Avail: yes

Find Seed or Plants

Find seed sources for this species at the Native Seed Network.

View propagation protocol from Native Plants Network.

Mr. Smarty Plants says

Native shade plants around fountain in California
March 18, 2009
Hi, we just put a fountain in our front yard. It is in a mostly shady area. I need to know what plants would go best around the fountain and survive in the shade.
view the full question and answer

National Wetland Indicator Status

This information is derived from the U.S. Army Corps of Engineers National Wetland Plant List, Version 3.1 (Lichvar, R.W. 2013. The National Wetland Plant List: 2013 wetland ratings. Phytoneuron 2013-49: 1-241). Click here for map of regions.

From the National Organizations Directory

According to the species list provided by Affiliate Organizations, this plant is on display at the following locations:

Santa Barbara Botanic Garden - Santa Barbara, CA
Tohono Chul Park, Inc. - Tucson, AZ
Native Seed Network - Corvallis, OR

Web Reference

Webref 38 - Flora of North America (2019) Missouri Botanical Garden, St. Louis, MO & Harvard University Herbaria, Cambridge, MA.
Webref 23 - Southwest Environmental Information Network (2009) SEINet - Arizona Chapter

Additional resources

USDA: Find Iris missouriensis in USDA Plants
FNA: Find Iris missouriensis in the Flora of North America (if available)
Google: Search Google for Iris missouriensis


Record Modified: 2023-02-14
Research By: TWC Staff

Go back