In angiosperms, about 30% -- 80% of species were estimated to be of polyploid origin. Polyploidisation is a key evolutionary process in higher plants that lead to the formation of new species. The majority of higher plant species evolutionised this way, or by means of hybridisation with more or less widely related species and further polyploidisation. This book presents and discusses research on meiotic division abnormalities, specifically cytoskeleton aberrations in karyo- and cytokinesis, leading to 2n gametes formation in plants, which includes 40 meiotic restitution mechanisms in pollen mother cells.