Sun and shade leaves? Cuticle ultrastructure of Jurassic Komlopteris nordenskioeldii (Nathorst) Barbacka

An ultrastructural transmission electron microscope (TEM) study of fossil l eaf cuticles from the Jurassic pteridosperm Komlopteris nordenskioeldii (Na thorst) Barbacka from the Mecsek Mountains (South Hungary) was conducted. R emnants of cuticles of leaves originating from so-called "sun and shade" en vironments were sectioned with a diamond knife, transversally as well as lo ngitudinally. Although the present study showed a simple type of cuticle in this pteridosperm, differences were observed in the occurrence of its comp onents, such as electron lucent amorphous material and various densities of granules, which give rise to different zones. The included fibrilous eleme nts appeared to be made of aggregated and aligned granules, equivalent in s ize and electron density to nearby non-fibrilous granular regions. The comb inations of these ultrastructural features allow distinctions between four types of cuticle: sun upper, sun lower, shade upper and shade lower. Consid ering the distinction made earlier in two types of cuticle and supposed to be related to sun and shade on the basis of macroscopical and microscopical features, four types only on the basis of differences in thickness, the pr esent study reinforces the distinctions with ultrastructural microcharacter istics. As this study shows the variations in ultrastructure of cuticle amo ng the four types, the differences observed may reveal the great sensitivit y of some plants to environment. At the same time, it points out the import ance, in ultrastructural studies of cuticles, of studying a number of sampl es for one taxon. (C) 2001 Elsevier Science B.V. All rights reserved.