PHYLLOTAXIS: OPEN AND CLOSED SYSTEMS

The inflorescence of Symplocarpus foetidus constitutes good material to analyse the biological processes and physical constraints involved in the development of plants. During the development of the inflorescence, two morphogenetic periods can be distinguished (i) before and (ii) during and after the development of floral parts. In the first period, when the floral primordia appear, the phyllotactic system could be explained by global processes at the inflorescence level. In the second period, the development of floral parts produces patterns which can be explained by local processes at the floral level. In this analysis the author defines the concepts of open system and closed system in phyllotaxis. In a closed system (e.g. spadix) the elements are arranged on a continuous and closed surface. In an open system (e.g. shoot apex) the elements appear on a surface periodically renewed and are removed from each other by the intercalary growth.