The leaves and shoots of plants are covered by a thin layer of lipids, usually called epicuticular waxes, which consist of a large amount of different aliphatic and cyclic compounds. While many species are covered by an unspecific thin film or smooth layer of waxes, others show very characteristic and morphologically complex wax struc-tures. Most of these structures originate by self-assembly due to their specific chemistry and are generally accepted to be crystals. With very few exceptions, the individual form and distribution of wax crystals is independent of environmental influences. During the last 20 years we carried out a representative study of angiosperm epicuticular waxes (15.000 species of almost all families) to gain a better knowledge of the systematic significance of epicuticular wax micromorphology. This resulted in the recognition of 23 distinct forms of wax crystals or orientation patterns of wax crystals. It became evident that major lineages above familiy level can be circumscribed by particular wax types. In Liliopsida, two groups became apparent: Lilianae are characterised by parallel platelets (Convallaria-Type) while longitudinally aggregated rodlets (Strelitzia-Type) are found in Commelinanae. Among the more basal angiosperms, the Magnoliales and some members of the "paleoherbs" (Aristolochiaceae) are characterised by transversely ridged rodlets containing the symmetric ketone palmitone (Aristolochia-Type). The Ranunculiflorae, as circumscribed by Dahlgren, exhibit small wax tubules built up by the secondary alcohol nonacosan-10-ol. The occurence of these tubules provides evidence for a position of Nelumbo close to Papaverales and Berberidales and indicates a closer relation between Trochodendraceae, Euptelelaceae, and Winteraceae.

Key words: angiosperms, cuticle, epicuticular waxes, systematics, ultrastructure