Cloning in vivo and in vitro of adult or mature woody plants is adversely affected by characteristics accompanying maturation such as reduced growth rate, reduced or total lack of rooting ability or sometimes the unpleasant phenomenon of plagiotropy (1, 2). Maturation, a complex phenomenon, is the major problem preventing a wider application of tissue culture technology among woody spieces. Despite the problems mentioned, the possibility of multiplying mature trees by cloning and establishing field trials with micropropagated material, has been demonstrated e.g. for eucalypts (3), Tectona grandis (112) Sequoia sempervirens, Pinus pinaster and Pinus radiata (4, 5). Success with these trees has been achieved mainly by the use of special starting material e.g. from the base of the tree, by special pre-treatment in vivo and/or by in vitro culture (6). All of these tricks, which improve propagation are often described by the general term rejuvenation; a term which is difficult to appreciate since it usually does not say what it in fact entails. However, it is clear that rejuvenation is a prerequisite for possible cloning of adult trees and that the success in practice will mainly depend on the ability to rejuvenate them (7, 8, 9, 10).