|dune thistle, pitcher's thistle, sand dune thistle|
|(Torr. ex Eat.) Torr. & Gray|
The following Participating Institutions are custodians for this species in the CPC National Collection:
The Holden Arboretum
Chicago Botanical Garden
The conservation of Cirsium pitcheri is fully sponsored.
Lindsey Parsons contributed to this Plant Profile.
This herbaceous plant grows for 5-8 years before flowering. It blooms and sets seed once in its life. It stays open from June until September, and is visited by up to 30 different insect species. When it flowers, it has one stem, and many branches. The entire plant can be up to 3 feet tall. The blossoms are cream or pink colored. The leaves are finely but deeply lobed, and can be up to 1 foot in length. The stems of the plant have fine hairs on them, which is an adaptation to its beach environment, so it can retain water and reflect the sun. It has a long taproot, growing up to 6 feet long.
Prior to flowering, this plant is found as a rosette with a cluster of leaves that are blue-green and covered in dense white wooly hairs. The plant is fairly stout and prickly. The entire plant is blue-green and covered in dense white wooly hairs. Mature leaves are divided deeply into narrow, spine tipped segments. The flower heads are also prickly and spine tipped. The heads are relatively large, and the seeds have feathery bristles. The seeds germinate in June, while the plant flowers and fruits from June until early September. Plant flowers and fruits from late June to early September.
Distribution & Occurrence
Pitchers thistle is found only on the open sand dunes along the shores of the western Great Lakes. (Bell et al. 2002)
|There is one population at Sleeping Bear National Lakeshore
One population in Ludington State Park/Manistee National Forest
Occurs in two Michigan Nature Association Sanctuaries
Occurs in several Natural Areas
1 population in Pictured Rocks National Lakeshore
Occurs at 12 sites in Canada (Great Lakes)
136 occurrences in the U.S. (Great Lakes)
Reintroduction by U.S. Fish & Wildlife at Illinois Beach State Park resulted in the establishment of approximately 100 plants.
Conservation, Ecology & Research
Seed predation on this species comes in many forms. It was found that American Goldfinches consumed as many as 50% of all the seeds in a flower head. Thirteen-lined ground squirrels were also observed preying on undispersed seeds, while birds, notably sparrows, ate unburied dispersed seeds. Spittlebugs cause damage to the plant.
The flower head weevil (Rhinocyllus conicus), an insect introduced from Europe to control weed thistles in pasture and rangelands, could potentially impact already threatened populations of Cirsium pitcheri. (Mlot 1997)
Shoreline recreation activities
Dune and shoreline stabilization
Misidentification and eradication
Research by individuals at Chicago State University, the Morton Arboretum, and Chicago Botanic Garden have been working on reintroducing this species to Illinois since 1991. This work has included genetic and life history studies.
1999. A Forester's Field Guide to the Endangered and Threatened Plants of Michigan's Upper Penninsula. Mead Corporation, Champion International Corporation and Shelter Bay Forests, Inc.
Pepoon, H.S. 1927. An Annotated Flora of the Chicago Region. Chicago, Illinois: The Chicago Academy of Sciences. 554p.