An Etymological Dictionary of the German Language/Annotated/Zweig
Zweig, masculine, ‘branch, bough, twig,’ from the equivalent Middle High German zwîc (-ges), neuter and masculine, Old High German zwîg, masculine; corresponding to Anglo-Saxon twĭg, English twig, Dutch twijg; also in Middle High German and Old High German zwî (genitive zwîes), neuter. The g is probably evolved from j, and zwî, genitive zwĭges, may be traced back to a nominative zwîg. The Anglo-Saxon form twĭg is implied by the accusative plural twĭgu (twiggu). Yet the primary forms cannot be ascertained with certainty, hence it is not quite clear how Zweig is connected with the numeral zwei (Zweig, Ut. ‘a division into two parts’?).