Observations on Changes in the Weed Flora of Mackinac Island - Michigan 1861-1994
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SubjectWeed Flora; Mackinac Island; Michigan; 1861-1994; Michigan Academy of Science Arts and Letters Annual Meeting - March 10, 1995; University of Michigan
Paper given at the Michigan Academy of Science Arts and Letters Annual Meeting, March 10, 1995 The first significant summary of weeds observed on Mackinac Island was by Henry David Thoreau in his diary on a visit from June 30 to July 4,1861. He listed 27 species of which 13 were listed as common (Table 1). Note the changes in abundance on the left side of the table, Dodge 1913, Overlease 1995. In trying to reconstruct a concept of the weeds of the Island in 1861, 134 years ago from his notes, we find Achillea millefolium (millfoil) "quite common"; Chrysanthemum leucanthemum (white-weed) "all over the Island"; Cynoqlossum officinale (houndstongue) "most conspiciaus and prevailing large weed"; Lithospermum officinale (gromwell) "very common"; Taraxacum officinale (dandelion) "very abundant". Comparing Thoreau's observations with recent collections and observations noted on the left side of the table,'we find that nearly all species have maintained their abundance and presence over the years. These important observations by Thoreau were brought to my attention by Ed Voss., University of Michigan.