Leaf and stem epicuticular wax structures in Lonicera species (Caprifoliaceae)

Epicuticular waxes are found on the surface of the plant epidermis as crystal structures which show morphological diversity and may be useful in plant systematics. The aim of this study was to recognise the diversity of the epicuticular wax cover on leaves and stems of Lonicera species (Caprifoliaceae) and to estimate the taxonomic value of wax traits. Adaxial and abaxial sides of the leaves and the stem surface in 35 taxa were investigated through a scanning electron microscope (SEM). The assessment was prepared on the basis of the presence or absence of basic types of wax structures and their dimensions, using categorical response analysis, multiple correspondence analysis and cluster analysis. In the analysed species, we found differences in the wax layer structure on the surfaces of the leaves and stems. Apart from the smooth layer, tubules and platelets can be found. Tubules are considerably more frequent than platelets. In many cases, the same plant part produces more than just one wax type. Our analysis indicates that wax structures are not very informative for the taxonomy of Lonicera, because we observed only a weak correspondence between the presence or absence of some types of wax tubules and the infrageneric classification of the genus. However, in particular cases these new data can be used for species identification.