Hymenoxys herbacea = H. acaulis var. glabra (Lakeside daisy) is an endangered Great Lakes endemic that is restricted to habitats of barren dolomite and limestone outcrops. It grows in only two locations in the United States: on the Marblehead Peninsula in Ohio and in northern Michigan. Lakeside daisy is also found in Ontario, Canada on the Bruce Peninsula and the Manitoulin Islands. An enzyme study of the species revealed low levels of diversity when compared to other rare taxa, high levels of genetic similarity between all existing populations and sub-populations, and no unique alleles to any population. Enzymes were not able to determine whether the lakeside daisy plants growing in Michigan were naturally occurring or introduced. Intersimple sequence repeats (ISSRs) have the potential to reveal more genetic diversity than enzymes. The purpose of this study was to examine levels of ISSR marker diversity within and between known populations of lakeside daisy and to investigate the origin of the Michigan population. A combined total of 261 individuals were collected from the Ohio, Canada and Michigan sites. Three ISSR primers were used for amplification and produced a total of 43 bands. Within population dissimilarity values (lowest similarity) were on average 0.185 and ranged from 0.102 to 0.221. The average among population dissimilarity value was 0.261 and ranged between 0.201 to 0.335. There were no bands unique to specific locations. There was also not enough among population variation to determine the origin of the Michigan plants. Because ISSRs revealed more diversity among populations than enzymes, future studies should include a greater number of ISSR primers. This may allow the detection of even more genetic variation and possibly identify geographically unique markers.

Key words: Hymenoxys herbacea = H. acaulis var. glabra , endangered plant, genetic variation, ISSR, Lakeside daisy