The agricultural sector of medicinal (including plant stimulants) and aromatic plants is characterized by an enormous number and diversity of species. Only a few of them can be considered cultivated crops in which significant breeding efforts are made. For most species, however, breeding is performed in short-term projects only. Therefore, basic knowledge about these species is still fragmentary. Our intention is to compile and organize the available information on the most commonly utilized plant species into one publication, thereby providing a standardized resource for the researchers and the grower community. This book therefore provides reference source materials for a wide variety of plant species used for human consumption due to their flavor, medicinal or recreational properties. It is divided into a section of general topics on genetic resources, breeding adaptation of analytic methods and a compilation of basic data for DNA content, chromosome number and mating system followed by a section of 20 monographs on a species or species groups.