Biologie und Ökologie von Chelidonium majus (Papaveraceae)
Chelidonium majus is a typical species of old settlements. Although being one of the most widespread plants in Central Europe, its germination biology is hardly known. Information on its floristic status are unclear too. We have checked therefore critically the information on its morphology and living mode. Its germination was investigated under different conditions. The monthly germination rate shows a clear optimum in spring time (March till June with a maximum in April.). This corresponds to the germination behaviour in nature. The nitrophilous behaviour of Chelidonium majus was proven by our experiments: its germination was the most successful in 0,001 mol KNO3 solution, the highest at room temperature. The lowest germination rate was found at 10°C. We carried out also competition tests with plants which are often associated with Chelidonium majus: Geranium robertianum, Aegopodium podagraria, Alliaria petiolata and Urtica dioica. As result we can say that Chelidonium majus is a relatively week competitor. Especially when competing against Urtica dioica and Alliaria petiolata a clear depression of biomass and growing height has to be noted, whereas Geranium robertianum was the weakest competitor as expected. All mapping results in Central Europe indicate a strong liaison to human settlements, seldom findings at forest edges are not in contradiction but have to be associated with rubbish or garden waste disposals. Chelidonium majus is myrmecochorous, obviously an effective long distance dispersal is missing. The high nitrophily was presumably a spreading barrier in former times where nitrogen rich places outside of settlements have been rare. Based on own field investigations and on checking of the literature we assume that there was no growing place in natural landscape for Chelidonium majus before human settlement started. Following we post the hypothesis: Chelidonium majus is an archeophyt in Germany. The genus Chelidonium is divided into three taxa very similar to each other. It appears within a huge area between Western Europe and Eastern Asia: Chelidonium majus subsp. majus is the European taxon, Chelidonium majus subsp. grandiflorum is the Central Siberian -Chinese taxon, Chelidonium majus subsp. asiaticum is the Korean-Manchurian taxon. There is a gap of distribution in the area of Kazakhstan and the adjoining Western Siberia between the 60. and the 80. degree of longitude, which actually is not explainable. A survey of the association of Chelidonium majus in Central Europe was carried out having the focus on the diversity of the species combination but not on the syntaxonomy. As a noteworthy however surprising result we found that Chelidonium majus is the most frequently growing plant on old walls in Germany.