Dwarf Lake Iris (Iris Lacustris)

Hugging the ground in sun-dappled openings in mixed northern forests, the dwarf lake iris grows only in very special sites near the shores of northern Great Lakes. This diminutive wild flower is appreciated for its great beauty, extreme rarity and for its genetic potential. Rare to begin with because of its restricted habitat, dwarf lake iris is becoming rarer still because of shoreland development.

What Does the Dwarf Lake Iris Look Like?

Though small in stature, this iris catches the eye of every passerby when it is in full bloom. Like a miniature blue flag iris, the deep blue to purple blossoms appear first in early May, and most flowers have faded by early June.

The purple blossoms are enhanced by bright yellow crests that decorate the three main petals.
DNR Photo

Three-inch diameter flowers are held a mere 3 inches off the surface of ground; the leaves, arranged in fans, grow up to 6 inches long. The observant naturalist will see that the leaves and flowers emerge from delicate brown rhizomes (horizontal stems) that creep along the soil surface. Even when not in flower, the iris can be recognized by its leaves and by the way it grows in dense colonies.

What Growing Conditions Does the Dwarf Lake Iris Require?

The dwarf lake iris occurs only near the northern shores of the Great Lakes. In a few sites, in openings in white cedar and birch forests allow just the right amount of sun to penetrate the forest floor, the iris grows. It thrives in the cool air that flows off the lakes, and the thin, moist, sandy or rocky soil near the shores. Curiously enough, it also seems to grow well along well along the edges of some country roads in the same areas. One of the reasons that the dwarf lake iris is so rare is that it must have just the right combination of light, humidity, soil, moisture and temperature to live.

How Does This Iris Reproduce?

A perennial, this native wildflower lives for many years. It seems to reproduce mostly vegetatively, established plants sending out new rhizomes, thus increasing the size of a colony. It rarely reproduces from seed.

Where Does the Dwarf Lake Iris grow in Wisconsin?

Near the rocky and sandy shores of Lake Michigan and Lake Huron are the only places on the globe where this rare iris grows. In Wisconsin it occurs only in two counties: Door and Brown.

How Rare Is This Plant?

The plant is very rare, indeed. This rarity is due both to a limited amount of habitat and to increasing human disturbance of shoreline areas.

What Can I Do to Protect This Valuable Species?

The key to protecting this rare iris is to protect its habitat from destruction by construction and development. Beyond that, it is important to restrict the use of herbicides and pesticides, road salt and excessive trampling in the neighborhood of the plant. Picking the flowers prevents the chance of seeds being formed and sometimes results in the plant's being uprooted. Property owners on whose land the iris grows can help by keeping track of their iris populations and by reporting such information to the Bureau of Endangered Resources.

For more information, ask the Whitefish Dunes naturalist, (920) 823-2400.