Original paper

Flowers of Araliaceae: structural diversity, developmental and evolutionary aspects

Nuraliev, Maxim S.; Oskolski, Alexei A.; Sokoloff, Dmitry D.; Remizowa, Margarita V.

Abstract

Within Araliaceae, at least four groups are recognized to have significant deviations from the typical euasterid flower groundplan: (1) Asian Schefflera clade (incl. Tupidanthus), (2) Plerandra group, (3) Tetraplasandra and (4) Osmoxylon. The main trends of flower structure variation are: reduction of calyx, increase in number of stamen whorls, increase of overall flower merism or only of stamen number, increase or decrease of carpel number, congenital petal fusion with postgenital corolla closure into a massive calyptra, appearance of flower disymmetry or asymmetry during flower development or even from its very beginning. Loss of polysymmetry is strongly correlated with increase of organ number, at least in the androecium and in the gynoecium. Other trends show mosaic distribution between taxa studied. Our data suggest primitiveness of pentamerous tetracyclic polysymmetric flowers (possibly with dimerous gynoecium) in Araliaceae and multiple losses of this floral construction in the evolution of the family. Multistaminate and multicarpellate flowers are clearly derived types in Araliaceae.

Keywords

apialesaraliaceaeflower polymeryflower groundplanevolution