Discrimination between epicuticular and intracuticular wax in blackberry leaves: Ultrastructural and chemical evidence

Epicuticular wax on the adaxial leaflet side of blackberry (Rubus fruticosus) occurred as wax knobs and irregular-shaped platelets. Removal of the epicuticular wax by a collodion film revealed the wax-free cuticle surface. This allowed the selective extraction of epicuticular wax from the film and subsequently of intracuticular wax from the cuticle. Epicuticular wax amounted to approx. 90% of total cuticular wax, only about 10% were present as intracuticular wax. The epicuticular wax contained mainly alcohol acetates, free alcohols and esters with lesser amounts of fatty acids and alkanes. Intracuticular wax was composed of free alcohols, alcohol acetates and fatty acids together with small proportions of triterpenoid acids, alkanes and esters.