THE GEOMETRY OF THE INFLORESCENCE OF SYMP LOCARPUS (ARACEAE) - PHYSICAL OR BIOLOGICAL PROBLEM

There exists, in the Symplocarpus inflorescence, a global physical con straint between the flowers. Re expected this constraint ran be expres sed by a linear relationship between a flower's number of sides and th at of its neighbors, a relationship which roughly follows Aboav-Weaire 's law. However the slope of the estimated straight line is higher tha n that of the theoretical one. This deviation can be explained by the action of a constraint opposing the physical constraint which tends to ward the development of 6-sided flowers. in fact, the flowers are tetr amerous, and they tend to be 4-sided which constitutes a biological co nstraint opposed to the physical constraint The equilibrium between th ese constraints leads to a decrease in the average number of sides, fr om 6 (theoretical value) to 5.5 (measured value), and an unequal distr ibution of the floral types (with 4, 5 or 6 sides) depending of the lo cal vigor.