COMPLEX POLYANDRY IN THE MAGNOLIATAE - DEFINITION, DISTRIBUTION AND SYSTEMATIC VALUE

A revised definition of complex polyandry is presented for the Magnoliatae. The differences between primary polyandry and secondary (complex) polyandry are clarified. Fascicled stamens are probably not primitive in Magnoliatae. Complex polyandry finds its origin by an increase of stamens in an oligandrous framework. Multiplications of stamens occur either on primary complex primordia, which follow the regular phyllotactic sequence in the flower, either on a girdling primordium (ringwall). The primary primordia may be fully developed before a secondary proliferation of stamens takes place or provide room for more stamens by a continuing growth process. This happens by the development of a staminal tube (e.g. Malvales) or by the growth of a hypanthium (e.g. Myrtales). A typical floral vasculature is developed concomitantly with complex polyandry. Stamen trunk bundles (stamen fascicle traces) are correlated with preformed complex primordia and the absence of a hypanthium. The inception of a ringwall is responsible for a higher complexity in vasculature and for obscuring the identity of the trunk bundles. The presence of a hypanthium does not permit trunk bundle formation because stamens develop on a limited section of the hypanthial slope. In that case the vasculature is characteristically represented by few large bundles linked with the perianth and the androecium. The distribution of complex polyandry is plotted on a Dahlgrenogram and presented in a table. The systematic relevance of complex polyandry is limited to the lower taxonomic (e.g. familial) levels.