An Etymological Dictionary of the German Language/Wirsching
Wirsching, Wirsing, m., ‘borecole,’ first recorded in ModHG.; the word seems, however, to have been borrowed at an earlier period from Upper Italy, as is also indicated by the Fr. term, chou de Milan ou de Savoie. It is based on Lombard. versa (comp. Ital. verzotto), ‘cabbage, borecole,’ which is usually referred to Lat. viridia, ‘vegetables.’ Kohl and Kappes were borrowed at a much earlier period.