An Etymological Dictionary of the German Language/Annotated/Birke
Birke (Swiss Bilche, Birche), feminine, ‘birch,’ from the equivalent Middle High German birke (Upper German birche), Old High German bircha, birihha; compare Anglo-Saxon birce, English birch; also Dutch berk, Anglo-Saxon beorc, Old Icelandic bjǫrk, Gothic *bairka, feminine, or *bairkjô, feminine. This term, common to the Teutonic group, is one of the few names of trees of primitively Aryan origin (compare Buche); the pre-Teutonic form is bhergâ (bhergyâ) and corresponds to Sanscrit bhûrja, masculine, ‘a kind of birch’ (neuter also ‘birch bark’), Old Slovenian brĕza, feminine, Lithuanian bérżas.