Contribution au problème des fusions : la métatopie dans l'inflorescence de Cornus sericea (syn. C. stolonifera)

Abstract

The purpose of this study is to provide a contribution to the problem of organ displacement and to explain the organization of the typical inflorescence of Cornus sericea L. Our analysis is based on anatomical and morphological data from normal and subnormal specimens.The singular nodal structure of the "normal" inflorescence of C. sericea results from two generalized deformations, a concaulescence and a recaulescence, appearing simultaneously. This phenomenon is particularly visible on the first pair of paracladia. These paracladia are united with the primary axis along a certain distance, and the inflorescential bracts are displaced along their axillary branches. Analysis of subnormal forms indicates that nodal deformation has a particular morphological nature which probably results from the activity of an intercalary meristem in the nodal region. In the case of the normal inflorescence, this segment cannot be considered homologous to either a node, a caulome, or a phyllome.The appendages carried by the first and sometimes by the second pair of paraclads, are appendicular organs, homologous to the foliaceous inflorescential bracts that we see on many teratological forms and in other species of Cornus.