An Etymological Dictionary of the German Language/Gänserich
Gänserich, m., ‘gander, wild tansy,’ ModHG. simply, formed like Enterich, from an earlier Ganser (still found in many of the UpG. dialects; in Alsat. gunšter, MidG. gánsert), MidHG. ganȥer, also ganȥe, ganze, m., ‘gander.’ Comp. LG. gante, Scand. gasse for gásse, ‘gander’; see Gans. The plant Genserich is a corruption of an earlier Grenserich; comp. Fr. bec d'oie, Ital. piè d oca. The MidHG. and OHG. term is gręnsinc (even cęnsing also in OHG.).