Microspores and pollen grain in triploid Chondrilla juncea L. from unpolluted and polluted areas

Preliminary observations of plants collected at a natural locality in Jany (Zielona Góra district, Poland) suggested that in some plants dyads occurred mixed with more or less regular tetrads, monads, triads and polyads. Similar results were obtained in plants growing on an unpolluted site at an experimental field in Modlnica near Cracow and in a highly polluted area close to a postfloatation reservoir at the Żelazny Most copper mine near Rudna (Silesia). However, in the plants growing in contaminated soil a higher degree of degeneration processes was observed. Either dyads or tetrads prevailed in the capitula in the analyzed plants. In some of their loculi, dyads and tetrads were mixed with monads, dyads, triads and/or polyads. Microcytes and pollen grains of different sizes were common. The sterility of mature pollen grain was slightly higher in a plant from Żelazny Most (80-85%) than in its derivative from Modlnica (65-75%). Degeneration of whole anthers in the plant from the polluted locality was frequent. In some anthers the destruction of meiocytes started early, together with precocious abortion of the anther tapetum.