L. Lőkös szerk.: Studia Botanica Hungarica 27-28. 1996-97 (Budapest, 1978)

Csontos, Péter: Seed bank behaviour of Verbascum L. species

The decrease of germination success in the second year (1994) was caused by the late greenhouse exposition of the samples coupled with an unusual advent of summerlike weather. The germination success of Verbascum austriacum was fluctuating around the average of eight percent. Similar fluctuation in the number of germinated seeds was found in DUVEL'S experiment for V. thapsus (TOOLE and BROWN 1946). In case of V. lychnitis the average rate of germination was higher (19%), and its germination pattern also differed from that of V. austriacum. Instead of fluctuation around an average V. lychnitis showed an increased rate of germination in the latest years of the experiment. The results until now show that both species have persistent seed bank and that is more pronounced in case of V. lychnitis. The somewhat less expressed seed bank strategy of V. austriacum may be connected with adaptation to less disturbed habitats (FENNER 1985). Nevertheless, viable seeds of V. austriacum were also detected from deeper soil layers of abandoned vineyards (A. SENDTKO, personal communication). With respect to the question about frequency of seed banking species in the Verbascum genus the results of this paper support the presumption of wide incidence. The predictive method of THOMPSON et al. (1993) would lead the same conclusion, since small and more or less isodiametric seeds are characteristic for mulleins (MURBECK 1933, SCHERMANN 1967). From the viewpoint of taxonomic evaluation it is important that the five species studied until now belong to distinct infrageneric taxa (cf MURBECK 1933). However, an extensive study involving more species, would be welcome. In this respect the seed bank strategy of perennial and suffruticose species found in the eastern part of the Mediterranean Basin seems to be the most interesting to investigate as they are the least weedy representatives of mulleins. * Acknowledgements. I thank ERIKA LEHOCZKY, ÁGNES PALÁSTI, KATALIN GÉMES, LÁSZLÓ LŐKÖS and TIBOR KALAPOS for various helps during the field and laboratory work. This work was supported by the Hungarian Research Fund (OTKA, no. F01

3260). REFERENCES ARTIGAS, F. J. and BOERNER, R. E. J. (1989): Advance regeneration and seed banking of woody plants in Ohio pine plantations: Implications for landscape change. - Landscape Ecology 2(3): 139-150.