An Etymological Dictionary of the German Language/Rose
Rose, f., ‘rose,’ from the equiv. MidHG. rôse, OHG. rôsa, f.; comp. the equiv. Du. roos, AS. rŏse, E. rose; adopted in the OHG. period from Lat. rŏsa. Had the word been borrowed earlier, the Lat. quantity would have been retained in G. (in Lilie, from Lat. lîlia, the vowel was shortened, because lĭlja was the pronunciation in MidLat.). Lat. *rôsa is, however, implied also by the Rom. cognates, Ital. rosa and Fr. rose. A Lat. ŏ must have led in OHG. to the form *ruosa; comp. OHG. scuola, ‘school,’ from Lat. scŏla.