Aquarium of the Pacific - Online Learning Center - Species Print Sheet
The Douglas iris, also called the Pacific Coast iris, is one of three species of the genus Iris native to the west coast of North America. It is a fast growing, drought tolerant perennial plant that has purple flowers in early spring. The flowers attract insects and hummingbirds. This iris species requires little maintenance and naturalizes easily making it a sought after plant to use in a native plant garden. It was widely used by Native Americans as food, medicine, and a source of fibers for rope.
At the Aquarium
The Douglas iris is illustrated on The Wave’s ceramic mural, Rios de la Vida (Rivers of Life). The fountain, mural, and accompanying graphics illustrate the story of our Los Angeles and San Gabriel Rivers. Although not on exhibit in the Aquarium, this flowering plant is included in this animal database to expand on the information touched on in The Wave fountain exhibit.
Coastal ranges from Santa Barbara County north into mid-Oregon. Commonly planted in Southern California native plant gardens.
The Douglas iris prefers shade with moist soils containing ample organic matter. It grows naturally in coastal bluffs, prairies, and mixed evergreen forest communities. It is common in grassy places, especially near the coast, at elevations generally less than 100 m (325 ft).
The Douglas iris is a perennial herb that is usually evergreen. It grows from a creeping tuberous rhizome, a root-like horizontal stem growing just below the surface of the soil. It is distinguished by its double row of leaves that overlap like praying hands. The medium green colored leaves are long and linear with parallel venation. The flower stems are erect and simple. Blossoms appear from February to May. Native plant blossoms are usually a dark lavender or reddish-purple in color but subspecies have been hybridized for gardens to provide a variety of colors such as white, pale cream, yellow, and rose. Seed capsules form on the end of the blossom stems after the spent flower drops off.
This iris is typically 30-46 cm (12-18 in) tall with a spread of 30-60 cm (12-24 in) across.
Reproduction is by both plant division and seeds. The iris has a clumping rhizome system making it easy to propagate it by digging up the rhizomes, sectioning, and replanting them. When the plant is allowed to increase freely, it naturalizes and eventually forms extensive ground cover. The rhizome develops “nodes” or growing centers that store food and can send out roots and vertical stems to form a new plant. Seeds form in large capsules that turn from green to brown and open at the top when ripe. Seed dispersal is rapid with the seed gone from the capsule two days after capsule ripening.
The Douglas iris is not listed on the Threatened or Endangered U.S. Plant List. The plant can be invasive, forming large clumps and extensive ground cover. It is unpalatable to livestock because of its bitter taste so ranchers consider it to be a noxious weed.
The Douglas iris was first collected near Monterey, California by the Scottish botanist and explorer David Douglas who also discovered and gave his name to the Douglas fir.
Douglas iris had many uses in Native American cultures. The Monache tribe and Southern California Yokut tribes made flour from iris seeds. Coast Miwok dried the roots and made them into a tea that was used as a medicine to induce vomiting and the Modoc made them into a poultice to sooth sore eyes. Very fine silk-like cordage was made by using only a single fiber taken from the margin of the plant’s leaves. After removing the strands, Pomo and Klamath women cleaned off the tissue by scraping the fibers with a sharp oblong tool made from an abalone or mussel shell fastened to their thumb. The men twisted the threads into nearly 6.1 m (20 ft) long ropes about 13 mm (0.5 in) in diameter with a lasso at one end. These ropes were used to catch deer. The strength and flexibility of the fibers also made the cordage useful in the fabrication of string, fishing net which the men knotted, and snares for catching birds and other game.