Ranunculiflorae — delimitation, phylogeny, diversification

Abstract

Within the Ranalean complex the Ranunculiflorae form a natural entity that in all modern classifications re-appears more or less in the same circumscription, although at different rank and under different names. The Ranunculiflorae are so distinct from woody Ranales (Magnoliiflorae) that a higher (superordinal) taxonomic rank appropriately expresses their relative isolation and individuality. On morphological and phytochemical grounds, several families that at one time have been assigned to this alliance, have to be excluded from it, such as the Nymphaeaceae (but not Nelumbo), Nepenthaceae, and Paeoniaceae. Phylogenetic links of the Ranunculiflorae with magnolialean families may exist but are probably less tight than often assumed; the Illiciales are no vital link between the two major groups. In contrast to the “eudicot” concept it is argued that tricolpate pollen in the Ranunculiflorae originated independently from non-magnolialean dicotyledons. Attention is called to different themes of diversification in several families of the Ranunculiflorae.