Topophysis in Gymnosperms: An Architectural Approach to an Old Problem
Peter Del Tredici
Topophysis is defined as the organizational status of a meristem which is determined by its position on the plant and which remains stable through vegetative propagation (Halle, et al , 1978; Molisch, 1938; Roulund, 1976) From a practical point of view, this means that if a lateral branch of a woody plant is rooted or grafted onto a seedling rootstock, the resulting propagule will continue growing in the same non-vertical orientation it maintained while it was still attached to its parent trunk. Try as one might to correct this orientation by tying the leader to a stake, the branch will continue its plagiotropic (horizontal) orientation once it reaches the top of the stake. From the propagator's perspective, the effects of topophysis are problematic because the propagules do not replicate the growth habit of the plant they were taken from.
In order to be properly understood, the phenomenon of topophysis must be examined within the conceptual framework of tree architecture, as
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