An Etymological Dictionary of the German Language/Annotated/Pfirsich
Pfirsich, masculine and feminine (s after r as in Mörser and Hirse; yet Suabian pfêršiχ), from the equivalent Middle High German pfërsich, masculine, ‘peach’ (compare Italian pesca, French pêche, whence English peach). Although the word is not recorded until the 12th century, Latin persicum was naturalised in Germany even prior to the Old High German period (so too in England; compare Anglo-Saxon persoc), as the permutation of the initial p to pf indicates (compare Lärche and Pflaume), while Birne was adopted within the latter era. With regard to the gender see Pflaume. With the introduction of horticulture and fruit-growing from the South, numerous names of fruit passed into German; see Kirsche, Pflaume, and pfropfen.