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Diagrammatic representation of the architectural sequence of development in Fraxinus excelsior (from Barthélémy et al.,1997a; highest category axes are not represented). The young plant expresses step by step (A and B) its architectural unit (in B) and then duplicates it automatically in the following stages of development (C and D) finally to give rise to a complex mature crown made of a succession of reiterated complexes (D).
