Which is generally considered an introduced species, Centranthus  or Arabis?
Centranthus:  Some "Centranthus" are known as introduced species in other parts of the world, including "Centranthus ruber" in the western United States and "Centranthus macrosiphon" in Western Australia. Arabis: Arabis , or rockcress, is a genus of flowering plants, within the family Brassicaceae, subfamily Brassicoideae.
Centranthus