The application of new molecular technology has greatly increased our understanding of the role of chromosomal change in plant evolution. There is now a broad database on genome size variation within and among species and a wide array of nuclear and cytoplasmic genetic markers. There is a variety of literatures addressing this subject but much of it is scattered. This book created a contemporary synthesis or work in this area and addresses issues such as herogeneity, polyploidy, chromosomal rearrangements within species and phenotypic consequences of chromosome doubling.