Preliminary observations on the flowering and seed production of the thistle Carlina onopordifolia Besser

Abstract

The paper deals with the flowering and seed production of thistle Carlina onopordifolia Besser, one of the rarest species in the flora of Poland. Bad weather conditions and shading were found to exert an unfavorable effect on the flowering, fruiting and seed viability. Isolation of the inflorescences had a similar influence, however it did not prevent seed setting. The results obtained including the lack of pollen germination on the stigma and the lack of pollen tubes in the styles, give the basis for supposition that Carlina onopordifolia reproduces apomictically.