Hill’s thistle (Cirsium hillii) COSEWIC assessment and status report: chapter 15
Collections examined and fieldwork conducted
No herbarium collections were examined for this status report, since label data had been compiled previously as part of the Rare Vascular Plants Atlas of Ontario Project, and by others for different projects. Distributional, and other information, was accessed using the hard copy file for Cirsium hillii at the Natural Heritage Information Centre in Peterborough. This included Rare Species Field Reporting Forms prepared in 2001 by J. Jones from 2000 fieldwork, and a printout of M.J. Oldham’s records of C. hillii from Ontario.
Fieldwork to verify localities for the status report was conducted by the author from August 5 to August 8 2002 on Manitoulin Island and the Bruce Peninsula at Sites: 34, 32, 33, 44, 46, and 55. Brief visits were made to Sites 9 and 12 in June of 2002, with incidental observations of Cirsium hillii.
As well, unsuccessful searches were carried out for this report in suitable habitat by the author on the following sites (UTMs are NAD 27):
- Great La Cloche Island - 6 August 2002 at UTM 0438620 5094052 in a degraded alvar dominated by Danthonia spicata and Schizachyrium scoparium, but with Ambrosia artemisiifolia throughout.
- Little La Cloche Island – 6 August 2002 at UTMs 0440925 5093106 and a good quality shoreline alvar at 0440907 5093711.
- Carter Bay, Manitoulin Island – 7 August 2002 at several stops along the access road to the shoreline dunes.
- Northwest of South Baymouth – 7 August 2002 with several forays off Hwy #6 to locate the C. hillii populations.
Note: Surveys conducted on contract for the Ontario Ministry of Natural Resources in September 2003 (following the completion of this report) identified 4 new sites and documented additional data for three other known sites; all new data have been added to this report (E. Haber, Feb 2004).
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