Pitcher's Thistle (Cirsium pitcheri)
Distribution & Habitat
How You Can Help
Did You Know?
Distribution & Habitat
Pitcher's Thistle grows only on shorelines or sand dunes of the Great Lakes
in Michigan, Indiana, Wisconsin and Ontario, Canada. It is restricted to the
dunes of Lakes Michigan and Huron and a few dune sites along Lake Superior.
Pitcher's Thistle was once found in Illinois on the shore of Lake Michigan, but
is now extirpated there. Michigan has more locations for this thistle than any
This shoreline plant requires open, windblown sand dunes or low, open beach
ridges. Pitcher's Thistle withstands the desert like environment of Michigan's
sand dunes by having a root capable of penetrating more than 6 feet into the
sand. The silvery hairs covering the plant aid in water retention and reflect
some of the sun's strong rays. On dunes it may be found growing with the
glossy-leaved dune grasses, the red fruited Bearberry, the bright yellow orange
Puccoon, and the beautiful blue Bellflower.
The Great Lakes dunes, formed principally between 5,000 and 14,000 years ago,
are a unique and irreplaceable component of Michigan's natural heritage. In
addition to being the only home for Pitcher's Thistle, the Great Lakes dunes are
the largest system of freshwater dunes in the world.
Pitcher's Thistle is a handsome, white flowered thistle. The plant's silvery
appearance is due to dense, white, woolly hairs covering the bluish-green leaves
and stems. It may reach a flowering height of 3.5 feet, although flowering
plants as small as 5 inches have been seen. The leaves are up to I foot long and
deeply divided into narrow, often spine tipped segments. The prickly flower
heads bloom from June to September and are cream-colored or slightly pinkish,
with a faint pleasant smell. The plant may be found in two stages: flowering and
non flowering. A non flowering or juvenile plant is a rosette or cluster of
silvery leaves. Juvenile plants take 2 to 8 years to mature to the flowering
stage. After flowering and setting seed, adult plants die.
This silvery thistle can be confused with another common dune plant called
Wormwood. Wormwood's leaves are more finely divided and are often purple at
their base. Wormwood also lacks spines. Other Michigan thistles have pink to
purple flowers, lack the silvery appearance, and are very prickly.
Pitcher's Thistle is found only on the dunes and shoreline of Lakes Michigan,
Huron, and Superior. It is threatened by loss of habitat due to increased human
activity in shoreline areas. Heavy foot and vehicular traffic in dune areas and
along the shoreline represent major threats. Pitcher's Thistle is listed as a
"threatened" species by the federal government and the state of Michigan. A
permit is required for any project (including research, development, and
construction) which may "take" or "harm" threatened or endangered species in
In addition to aesthetic, ethical, and ecological reasons for protecting
Earth's diverse species, another reason can be offered: self-interest. The
natural world is our life support system, providing countless medical,
agricultural, and commercial benefits. For example, chemicals from plants are
the sole or major ingredient in one quarter of all prescription medications in
the United States. Scientists have shown that closely related plants usually
have similar chemical compounds. Guayule (pronounced gwhy ool' Iee), a drought
tolerant shrub of the American Southwest in the same family as Pitcher's
Thistle, is being reviewed as a commercial source of natural rubber and may help
limit U.S. dependence on imported natural rubber. If we choose to save wild
species now, they may offer opportunities for us in the future. We do know that
when a species becomes extinct, a unique set of genetic material whose use
presently may be unknown, is lost forever.
To conserve the remaining populations of Pitcher's Thistle, private,
corporate, and public landowners and land managers who are likely to have
Pitcher's Thistle on their property are being contacted. Landowners have the
opportunity to assist in the preservation of this remarkable component of
Michigan's natural heritage. Other cooperative conservation efforts initiated by
the Natural Heritage Program include:
- protecting habitat within public natural areas and private nature
- completing extensive surveys of known and potential habitat of threatened
plants and animals, and
- developing management plans with public agencies and private developers
through statewide permitting and enforcement systems.
How You Can Help
- Voluntarily protect coastal dunes and shoreline habitat where this and
other special plants and animals of the Great Lakes live.
- Learn the differences between Pitcher's Thistle and Wormwood.
- Report your observations, including possible new locations of Pitcher's
Thistle, by contacting the Michigan Department of Natural Resources.
- Report destruction of this plant or the habitat in which it occurs by
calling the Report All Poaching (R.A.P.) Hotline at 1 800 292 7800.
- Become involved with a land conservation organization.
- Support the Nongame Wildlife Fund by purchasing a
wildlife habitat license
plate, or through a
Did You Know?
Pitcher's Thistle, also known as Dune Thistle, was named in honor its
discoverer, Dr. Zina Pitcher. He was a prominent citizen who helped organize the
Historical Society of Michigan and the University of Michigan's medical school.
While serving as an army surgeon during the 1820's at Fort Brady, Sault Ste.
Marie, Dr. Pitcher found this thistle on the Grand Sable Dunes of Lake Superior.
Dr. Pitcher, like many early physicians, was also an accomplished botanist.
information was written by Elaine A Chittenden with assistance from the Natural
Heritage Program and Michigan Natural Features Inventory staff.