Although genetically identical, the propagation material may be effected from the position on the mother tree from where it was collected, and permanently or temporarily continue to show signs of this origin. For example, it may continue to grow like a branch when it is used as scion, cutting or air-layered material. The phenomenon is called topophysis or plagiotropic growth. Periphysis is another phenomenon where plant material shows characteristics according to the place of the tree from where it was collected, e.g. sun branches or shade branches.
Scions for grafting and material for air-layering should usually be taken from new shoots of mature trees. For cuttings, hedged plants are usually the best source of juvenile material.
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| Grafted plants: The trees on the left show a normal upright growth form (orthotropic growth while those on the right tend to grow like branches (plagiothropic growth). | |
