Synonyms: Western Blue Flag | Rocky Mountain Iris A hardy rhizomatous perennial with sword-like leaves are bluish-green, blue to pale lilac flowers resemble common garden Iris but are smaller. Blooms April-June; usually flowers the 3rd year. Persists in moist meadows and streambanks from low valleys to 9,000 ft. elev.; SD to BC, south to CA, AZ, and Mexico. Prefers full sun, moist soils; great for the rock garden, spreads readily.