STRUCTURAL AND ARCHITECTURAL ANALYSIS OF THE INFLORESCENCE OF BEGONIACEAE

The inflorescence structure of Begoniaceae was analyzed taking into ac count their degree of symmetry. Qualitative and quantitative analyses of 71 species led to the recognition of nine architectural models. Whe n the whole plant is considered, the inflorescence of Begoniaceae is a thyrse. Comparative analyses of the models allowed to determine at wh at level symmetry or asymmetry is found. There is a correlation betwee n the total lengths of axes and between flower numbers on the best and least developed sides of an inflorescence. For the whole family, the difference between the two sides of the inflorescence is significant f or the former, and not for the latter. Divergence angles on the best d eveloped side do not differ from those on the least developed one for a same ramification, and likewise between successive levels of ramific ation. Thus, the inflorescence appears asymmetrical if total length of axes is considered. These results tend to support the hypothesis that the Begoniaceae are fundamentally asymmetrical. Inflorescence symmetr y is found in some groups by stabilization and compensation of differe nt asymmetric components at the global and local levels. Nevertheless, inflorescence asymmetry does not seem to be related to plant architec ture, although it seems to be related to the degree of foliar asymmetr y.