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Pitcher's Thistle

   Photo: Donald Kirk

Features: Pitcher's Thistle (Cirsium pitcheri) grows on relatively undisturbed sandy shorelines and on old dunes stabilized by vegetation. It has prickly leaves which are characteristic of thistles, and the stem and underside of the leaves are densely covered with white hairs. Pinkish-white flower heads, which provide a source of nectar for bees and other insects, are produced in mid-summer. Seeds have a downy white "parachute" and can be carried by the wind some distance from the parent plant.

Status: Threatened Provincially, Special Concern Nationally

Range: The global distribution of Pitcher's Thistle is restricted to the Great Lakes basin in the United States and Canada. The species has declined severely and is identified as endangered, threatened or extirpated throughout its entire United States range. In Canada it occurs only at four sites; two places on the Lake Huron shoreline south of the Bruce Peninsula; on Manitoulin Island; and at one location on Lake Superior.

Threats: This species' shoreline habitat is very fragile, and has been subjected to considerable human impact. Habitat loss has occurred as a result of cottage development; erosion caused by the excessive recreational use of beaches; and changes in normal sand buildup due to shoreline modifications.

Protection: Pitcher's Thistle is protected under Ontario's Endangered Species Act, 2007. This Act protects the species from being killed, collected or harmed. Two Ontario populations of Pitcher's Thistle occur in Provincial Parks, and one site is in Pukaskwa National Park. Plants at these sites are being monitored. The Natural Heritage component of the Provincial Policy Statement under Ontario's Planning Act provides for the protection of significant habitat of endangered species. Additionally, the federal Species at Risk Act (SARA) protects Pitcher's Thistle on the federal lands on which it occurs.

Text Sources: Keddy 1988; Maun 1999

Last Modified Date: June 2011

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