Chemical Composition and Surface Structures of Epicuticular Leaf Waxes of Ginkgo biloba, Magnolia grandiflora and Liriodendron tulipifera

Epicuticular leaf waxes of Ginkgo biloba, Magnolia grandiflora and Liriodendron tulipifera contain homologous series of hydrocarbons, wax esters, benzyl acyl esters, aldehydes, primary alcohols, and fatty acids. None of these lipid classes is found to contain any main component dominating. In addition to these usual wax lipids, in G. biloba leaf wax a secondary alcohol namely nonacosan-10-ol (15.0%), y-tocopherol (1.7%) and acetates (0.3%) is also present. The wax of L. tulipifera, however, contains hentriacontan-16-one (23%) and several triterpenols (10%), additionally. On G. biloba leaves a dense arrangement of tubular wax crystalloids are found on the lower as well as on the upper leaf surface. The openings of the tubules can be seen very well in the SEM figures at a magnification of 20000. The small tubules are a clear indication for the pres­ ence of nonacosan-10-ol as also reported previously for conyferyl waxes. Leaves of M. grandiflora have an abaxial epidermis with a continuous wax layer without any crystalloids or sculptures. The adaxial epidermis also shows a continuous wax layer but with little irregular granular sculptures. L. tulipifera leaves show an abaxial epidermis with a continuous wax layer superimposed by a dense arrangement of crystalloids in shape of angular rodlets which are composed of several piled up layers. The adaxial leaf surface is also superimposed with wax crystalloids, the rodlets of which, however, are not sculptured in such definite way. They usually appear melted up and also form granular sculptures. The wax crystalloids in shape of angular rodlets on the abaxial surface are formed by hentriacontan-16-one. The abaxial and adaxial leaf surfaces show most different micromorphological wax ultrastructures, as shown for all trees studied.