The purpose of this book is to bring together the most recent knowledge concerning the genetic improvement of ornamental plant species. Active researchers of many aspects of the genetics and breeding of these species have written chapters organized into three sections: Cytogenetics, Quantitative Genetics and Molecular Genetics. These titles identify the basic tools used in a variety of breeding situations. Some are traditional and well established; others offer new and exciting challenges for the future. vii Introduction The purpose of this book is to bring together recent knowledge concerning the genetic improvement of ornamental plant species. In the 20th century flower breeding has become widespread leading to many improvements in phenotypic and production characteristics of ornamental species. These methods depends on the creation and subsequent selection of genetic vari- ability. Lack of variability in gene pools has been a chief limitation to the success of flower breeding. Recent progress in molecular biology makes it possible to add genetically well-defined characteristics to gene pools, thus increasing the potential for genetic improvement.These methods also enable the specific silencing of genetic information to accomplish an intentional loss of function. This book compiles current knowledge of the cytogenetics, quantitative genetics, and molecular genetics of ornamental plant species. The three sections identify the basic tools used in a variety of breeding situations.