Clonal forestry has come of age. Basic techniques in genetics and biotechnology of other organisms are generally applicable to forest trees. However, there are some differences, in particular in the juvenile- and maturation-related regeneration. Examined here are crucial topics of juvenility, maturation and rejuvenation in clonal propagation of trees. In addition, the genetics of clones, population biology of clonal deployment, propagation and field testing of clones, clone identification, clonal physiology, regeneration and variation in plant tissue cultures, the role of somatic embryogenesis in clonal forestry, and recent developments in biotechnology, including the molecular structure of trees and gene transfer are covered in depth.