Zur Evolution des Parasitismus bei denScrophulariaceae undOrobanchaceae

Different growth forms and life forms of parasitic plants inScrophulariaceae andOrobanchaceae were studied from a comparative point of view. The most primitive form of parasitism is found in small, annual root parasites. Small wart-haustoria in the hypocotylar region of larger root parasites point towards a tendency of these plants to form hypocotylar tubercles as primary haustoria. Wart-haustoria also can develop on scale leaves, demonstrating an evolutionary trend towards the most advanced form of parasitism in these two families the formation of large leaf haustoria.