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Bransford, W.D. and Dolphia
Iris missouriensis Nutt.
Rocky Mountain iris, Western blue flag
Synonym(s): Iris longipetala, Iris missouriensis var. arizonica, Iris missouriensis var. pelogonus, Iris pariensis, Iris tolmieana
USDA Symbol: IRMI
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. They are pale to dark, lilac-purple and haves yellow bases. The grayish-green leaves are relatively broad. Large, delicate, pale blue or blue-violet 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.
The only native species east of the Cascade Mountains and the Sierra Nevada, it often forms dense, large patches in low spots in pastures, where the tough leaves are avoided by cattle.
Plant CharacteristicsDuration: Perennial Habit: Herb Leaf:
Green Fruit: Size Class:
Bloom InformationBloom Color: Purple
Bloom Time: May , Jun
, 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 ConditionsWater 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.
BenefitUse 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
PropagationSeed Collection: Easily collected from the large capsules.
Seed Treatment: Not Available
Commercially Avail: yes
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.
Record Last Modified: 2009-02-20
Research By: TWC Staff