Evolution of the Arabis Hirsuta Group in Central Europe

Summary Cytological, cytogenetical, ecological, geographical and morphological aspects of differentiation in the Arabis hirsuta species aggregate are summarized in order to elucidate the evolution and phylogeny of this group in Central Europe. All species involved are self‐compatible. A. planisiliqua (Pers.) Reichenb. (s.l.), A. sagittata (Bertol.) DC. and A. allionii DC. (s.l.) are in the main diploids (2n = 16), and have originated by divergent differentiation. A. hirsuta (s. str.) is an allotetraploid (2n = 32); its possible descent from A. sagittata (Bertol.) DC. × A. ciliata Clairv. is discussed. The latter diploid species must be placed outside of the aggregate; nevertheless, experimental production of the hybrid with A. sagittata and its polyploidization has succeeded. The synthesized allotetraploid is rather similar to A. hirsuta (s. str.) but not identical with it. Further investigations are in progress.