Mary,I found the following info in the 1900 Census for Detroit, Michigan.
Henrietta Pohl-born Dec. 1849 in Germany widowed immigrated to U.S. 1864 daughter-Martha McClean-born Sept 1869 in Michigan son-Frederick-born Sept 1874 in Michigan occupation- Boxmaker son-Heugo-born March 1877 in Michigan occupation-Artist daughter-Charlotte-born Jan 1885 in Canada grand daughter-Flora McClean-born Nov 1887 in Canada daughter-Clarise-born May 1889 in Canada
charlotte-Flora-clarise immigrated 1895 They all lived at #233 Adams Avenue East Detroit, Michigan
I wasn't sure if this was your descendants you were searching for.It seems a bit co-incidental that Henrietta's info almost matches yours and that she had a son named Frederick.Good luck and i hope this helps if this is your family. Debi Z