Epicuticular wax ultrastructure and classification of Ranunculiflorae

Abstract

Epidermal surfaces of about 199 species from 66 genera of ranunculiflorous families are examined by scanning electron microscopy. The micromorphology of their epicuticular wax crystals is presented and discussed under taxonomic aspects. All families of the Ranunculifloraes. str. (Ranunculales, Papaverales) prove to be highly uniform: apart from a few exceptions they are characterized by the presence of clustered wax tubules (Berberis type), chemically dominated by the secondary alcohol nonacosan-10-ol in the species analysed. This is in marked contrast to the Magnoliidae s. str. (Aristolochiales, Laurales s. l., Magnoliales), which are almost uniformly defined by transversely ridged crystals of the Aristolochia type, chemically characterized by the presence of palmitone and the absence of nonacosan-10-ol. However, the Canellaceae, Nelumbonaceae, and Winteraceae produce the Berberis type tubules similar to Ranunculiflorae. This suggests a reconsideration of the position of these families and in particular for Nelumbo a close relation to the Ranunculiflorae also based on other chemical data. Within the polyphyletic Hamamelididae the ''lower'' families Cercidiphyllaceae, Daphniphyllaceae, and certain genera of Hamamelidaceae are also characterized by Berberis type waxes.