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U.S. Forest Service

Our Native Irises: Dwarf Woodland Irises

Iris lacustris: Dwarf Lake Iris

The dwarf lake iris occurs on the northern lakeshores of Lake Michigan and Lake Huron in Michigan, and Lake Michigan in Wisconsin.

Iris lacustris. Note how the nectar guides of this Iris lacustris direct bumblebees down between the style arm and lower portion of the sepal. Photo by Charles and Diane Peirce, Michigan Wildflowers.

Map of the range of Iris lacustris in North America. Range map of Iris lacustris. Courtesy of the USDA PLANTS Database.

Iris lacustris has a sky blue to deep blue to violet flower. The spreading sepals have a white signal bordered by a deep purple color. The inflorescence is one- to rarely two-flowered. The stiff upright leaves arise from narrow, creeping rhizomes that have an enlarged terminus with fibrous roots.

Iris lacustris is found growing in slightly acidic, shallow, moist, sandy, or rocky soils in sun-dappled, forested openings near the lakeshore where cool air flows off the lake and into the openings providing for an unusual microclimate.

Iris lacustris. The dark purple spot and red veined golden yellow crest prominently display the nectar guides of Iris lacustris. Photo by Charles and Diane Peirce, Michigan Wildflowers.

Iris lacustris seed capsule. Note the mature seed capsule of Iris lacustris in which the seeds begin to sprout within the pod as they are ready to be released to the environment. Photo by Charles and Diane Peirce, Michigan Wildflowers.

Conservation Concern

Iris lacustris is listed as threatened under the federal Endangered Species Act. Always rare, it has become rarer due to loss of habitat resulting from shoreline development.

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