You searched for: Institution University of Michigan. Libraries Remove constraint Institution: University of Michigan. Libraries Place Roadside ditch, ca. 1 mi. s.e. of Mackinaw City on U.S. Route 23. Remove constraint Place: Roadside ditch, ca. 1 mi. s.e. of Mackinaw City on U.S. Route 23. Topic Salix Remove constraint Topic: Salix