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Bransford, W.D. and Dolphia
Iris douglasiana Herb.
Douglas iris, Mountain iris, Western iris
Synonym(s): Iris douglasiana var. major, Iris douglasiana var. oregonensis
USDA Symbol: IRDO
USDA Native Status: L48 (N)
The rhizomes of Mountain iris or Douglas iris spread slowly, eventually creating a 2-4 ft. wide clump. Tufts of 1-2 ft., sword-shaped, dark-evergreen leaves arise from the rhizome and surround a flowering stalk of equal height. Several showy iris blossoms emerge from leafy bracts atop the stalks. The flowers are usually blue, though the colors can range from pale cream to yellow to reddish purple. Large, reddish-purple, pinkish, white, or cream flowers, with lilac veins, on stout branched stalks rising from clumps of sword-shaped leaves.
This is a common iris in the Redwood region. The genus name, Greek for rainbow, refers to the variegated coloration of the flower. In Greek mythology, Iris, a member of Heras court and goddess of the rainbow, so impressed Hera with her purity that she was commemorated with a flower that blooms in the rainbow colors of her robe.
Plant CharacteristicsDuration: Perennial Habit: Herb Flower:
Fruit: Size Class:
Bloom InformationBloom Color: Blue
Bloom Time: Mar , Apr , May
, OR Native Distribution:
Coastal region from Santa Barbara Co., CA
to Coos Co., OR Native Habitat:
Grassy slopes; open woods
Growing ConditionsLight Requirement: Part Shade
Soil Moisture: Moist
Soil pH: Acidic (pH<6.8)
Soil Description: Moist to dry, nutrient-rich soils.
Conditions Comments: Douglas iris is a vigorous, shade and drought tolerant iris. Crosses with I. innominata and other West Coast species are collectively called Pacific Coast hybrids.
BenefitConspicuous Flowers: yes
Increase by seed or rhizome
divisions. Divide rhizomes in late fall or early spring but cutting the leaves back to about 5 in. and then cutting between the tufted clumps. Plant fresh seeds in early fall in permanent location or flats that are left out o Seed Collection:
Easily collected from the large capsules. Seed Treatment:
No pretreatment is necessary, although a moist stratification (3 mo. at 40 degrees) may be beneficial. Commercially Avail:
From the National Suppliers Directory
According to the inventory provided by Associate Suppliers, this plant is available at the following locations:
Oregon Native Plant Nursery
- Woodburn, OR
From the National Organizations Directory
According to the species list provided by Affiliate Organizations, this plant is either on display or available from the following:
Santa Barbara Botanic Garden
- Santa Barbara, CANative Seed Network
- Corvallis, OR
Record Last Modified: 2009-02-21
Research By: TWC Staff