An Etymological Dictionary of the German Language/Annotated/Gänserich
Gänserich, masculine, ‘gander, wild tansy,’ Modern High German simply, formed like Enterich, from an earlier Ganser (still found in many of the Upper German dialects; in Alsatian gunšter, Middle German gánsert), Middle High German ganȥer, also ganȥe, ganze, masculine, ‘gander.’ Compare Low German gante, Scandinavian gasse for gásse, ‘gander’; see Gans. The plant Genserich is a corruption of an earlier Grenserich; compare French bec d'oie, Italian piè d oca. The Middle High German and Old High German term is gręnsinc (even cęnsing also in Old High German).