Dwarf Lake Iris

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Dwarf Lake Iris

Iris lacustris

ListedSeptember 28, 1988
FamilyIridaceae (Iris)
DescriptionDwarf iris with flat, narrow leaves and blue flowers.
HabitatPartially shaded, sandy or gravelly soils.
ThreatsShoreline development, road construction, succession.
RangeMichigan, Wisconsin; Ontario, Canada


Dwarf lake iris, Iris lacustris, a herbaceous perennial, is a diminutive iris with flat, erect, narrow leaves. The parallel-veined leaves stand 3 in (7.5 cm) tall when flowering begins in late spring, but later double in height. Flowers, which have three petals and larger, conspicuous sepals, are about 2.5 in (5 cm) long, and range in color from blue to dark violet. Dwarf lake iris is rhizomatous and forms dense colonies.


The dwarf lake iris is found along the shores of Lake Michigan and Lake Huron. It prefers sandy-gravelly sites in partial shade, and, according to the Forest Service, is an effective soil stabilizer.


Endemic to the shores of Lake Huron and Lake Michigan, dwarf lake iris is found in Wisconsin, Michigan, and Ontario, Canada. Reports of colonies along the shores of Lake Superior have been discounted. The species was previously more widely distributed, but shoreline habitats have been extensively altered by housing development, recreational use, and road construction. A historic population of dwarf lake iris near Milwaukee was lost to urban expansion.

In Michigan, the dwarf lake iris is found at 60 sites along the shores of Lakes Michigan and Huron. Several colonies occur on federal land in the Huron and Manistee National Forests and in the Hiawatha National Forest on the states's northern peninsula.

In 1986, 15 scattered colonies were reported in two counties on Wisconsin's Door Peninsula, but development and shoreline activity have resulted in a decline. One protected population occurs in the Ridges Sanctuary in Door County. In Ontario, plants are found on Manitoulin Island and the Bruce Peninsula.


The dwarf lake iris is threatened by habitat destruction and lack of active management. In both Michigan and Wisconsin, development and road construction pose the greatest threats to surviving colonies. Home construction, road widening, chemical spraying, and road salting, all degrade the plant's habitat.

Natural plant succession has left several colonies in nearly complete shade, which the plant cannot tolerate. The iris is listed as threatened by the state of Michigan, but fewer than 20% of the colonies in the state receive any form of habitat protection. Approximately 40% of the Wisconsin colonies are considered protected, but only a small portion are actively managed.

Conservation and Recovery

Wisconsin's successful landowner contact program, initiated in 1991, has helped numerous species, including the dwarf lake iris. The program, which involves voluntary participation, rigorous respect of landowners' rights and a personalized educational approach, seeks to protect endangered plants and animals that occur on private lands. This goal is carried out under a signed Memorandum of Understanding (MOU) between the landowner and the Wisconsin Bureau of Endangered Resources. By 1995, some 27 landowners and land managers along the shore of Lake Michigan had signed iris protection MOUs.

An example of how the private market can actually help the species in such situations comes from the example of a cooperative real estate agent, Richard Kielpikowski. Representing a seller on whose property the iris grows, Mr. Kielpikowski agreed to alert any potential buyer of the presence of this threatened species, saying that he viewed the iris both as a species he wants to protect and as a valuable feature of the property that might make it more attractive to potential buyers.

As an attractive flower, the dwarf lake iris has potential for commercial sale. Plantsalmost certainly collected from the wildare already being offered for sale in garden catalogs, and increased trade is a worry for conservationists. Cultivation of the dwarf lake iris to satisfy the commercial market should reduce any illegal trade.


U.S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
Federal Building
Ft. Snelling
Twin Cities, Minnesota 55111


Alverson, W. S. 1981. "Status Report on Iris lacustris." Report. Wisconsin Department of Natural Resources, Madison.

Guire, K. E., and E. G. Voss. 1963. "Distribution of Distinctive Shoreline Plants in the Great Lakes Region." Michigan Botany 2:99-114.

Planisek, S. L. 1983. "The Breeding System, Fecundity, and Dispersal of Iris lacustris." Michigan Botany 22:93-102.

Read, R. H. 1976. "Endangered and Threatened Vascular Plants in Wisconsin." Technical Bulletin No. 92. Scientific Areas Preservation Council, Wisconsin Department of Natural Resources, Madison.