Dune Thistle (Cirsium Pitcheri)

It may be difficult to convince some people that a thistle is rare and needs protection. But that is precisely the case with Pitcher's thistle. It is quite a different plant from the thistle that is pest in farms and gardens. Dune thistle is important for the lessons it teaches in evolution and adaptation - for its beauty and the role it plays in the dune plant community.

What Does the Dune Thistle Look Like?

Less prickly than other thistles, dune thistle has deeply dissected blue-green leaves with a downy surface.

The dune thistle's flowers have the familiar thistle shape, but are cream to pinkish-tan in color.
DNR Photo

During its first few years of life, this dune plant bears only a rosette of leaves at the surface of the sand. When matures, it sends up a 3-foot-tall stalk on which flowers appear.

What Growing Conditions Does the Dune Thistle Like?

The ideal site for this rare plant is an area between an open sandy beach and a fully vegetated dune. It is found in slowly changing dynamic dune systems where appropriate openings appear in different places for short period of time. It only grows on sand dunes next to the fresh water of the Great Lakes.

How Does the Dune Thistle Grow and Reproduce?

Dune thistle reproduces only by seed. After a seed germinates it sends a taproot deeply into the sandy soil. Mature plants have tap roots that extend 6 feet deep and more. A new seedling bears only a few strap-like leaves. During the next few years the plant forms a rosette of leaves at the surface of the sand. At last, after 5 to 8 years of growth, it sends up a flower stalk, blooming in early to mid-summer. Once seeds form and ripen the parent plant has completed its mission in life and dies.

Where Does the Dune Thistle Grow in Wisconsin?

The thistle is found mostly on Lake Michigan dunes, though there are also a few sites near the shores of Lake Superior. Within Wisconsin, the thistle grows only in Door, Manitowoc and Sheboygan Counties.

How Rare is This Plant?

This thistle is so rare that it is listed both by the State of Wisconsin and by the Federal Government as "Threatened." Indeed, its habitat, Great Lakes dunes, is threatened, too. Many second homes and condominiums are being built here. All-Terrain-Vehicles (ATV's) are doing more and more damage to dunes and the plants that grow here. Trampling by growing numbers of vacationers kills more thistle plants.

What Can I Do to Protect This Valuable Species?

The key to protecting this rare thistle is to protect its habitat from destruction. It is important to restrict the use of herbicides/pesticides and foot traffic in the neighborhood of the plant. Uprooting of the plant must be avoided. Property owners on whose land the thistle grows can help by keeping track of plant numbers and locations.

Whitefish Dunes State Park holds a Dune Thistle count each fall. Join the park staff and friends members in protecting this fragile plant.

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