XVI International Botanical Congess

A well-corroborated phylogeny of water lily genera has been achieved based on agreement between non-molecular data and DNA sequences hence clarifying the limits of the order Nymphaeales to comprise two clades, the Nymphaeaceae and Cabombaceae. When floral features were evaluated, the pleiomerous condition revealed several instances of secondary increases. It remains uncertain whether the Cabombaceae, having few perianth and essential parts, are reduced from a more complex pleiomerous flower or that all nymphaeaceous flowers acquired their pleiomery by secondary increases. Findings from a comparative study of floral ontogeny in Nymphaeales and Nelumbonales are presented that expand our perspective of evolutionary trends in these taxa.