Our understanding of the evolution of DNA content in angiosperm plants has improved in recent years. Genomes in angiosperms vary in DNA content over 1000-fold. Variations in plant genome size are primarily due to differences in ancestral polyploidy and the periodic burst in activity of retroele- ments. Genomic data show a strong correlation between the size of genome and the amount of retroele- ments. Gene duplication have contributed to the functional divergence of the duplicates, and have become a strong evolutionary force.