I have uploaded a spreadsheet of the rare/significant plant species here:

https://portal.nrsi.on.ca/public.php?service=files&t=3201959300eb1d0230af1f92540381fe

This includes both the 1999 Richardson & Martin List as well as the 1989 Riley list. You can use this to refer to but keep in mind that species not on this list but which you suspect could be quite uncommon or new to the Region would be of interest. I do not have a filter set for the project so in theory a member of the project could add Trillium grandiflorum (or all of their Waterloo plant observations) and they would get pulled in. Ideally reference to the spreadsheet will help to identify what is of interest to the project and what isn't.