Abstract: Epigenetic phenomena, heritable changes in phenotype, and hence in gene regulation, but not in DNA sequence, occur in the process of polyploidization in many plants. These phenomena include gene silencing, DNA methylation, nucleolar dominance, transposable elements activation and genomic imprinting. Epigenetic phenomena might be caused by gene silencing or alternative gene expression from intergenomic interaction. These could also be induced from the changes of histone coding, without DNA methylation. Furthermore, hypomethylation, chromatin reconstitution or transposable element activation could contribute to epigenetic phenomena. These modifications may give rise to the diversification of gene expressing, to the genetic and cytological diploidization, as well as to intergenomic coordnation. This paper reviews epigenetic phenomena in many plants and their influence on evolution of plant genome, thus hint the likely pathway of research in this field.