The developmental character of BPP is further supported by the incidence of BPP axillary stems. The frequency of BPP in axillary stems regenerating after bud abscission was significantly higher on bent main stems than on normal ones (Fig. 4), although BPP and straight stems may be found on the same plant. This finding implies that BPP stems varied developmentally from normal stems and this was expressed by the fate of the axillary stems. Therefore, whatever factor triggered BPP in a specific apical meristem, apparently also affected axillary meristems on the same stem.