Micromorphology and anatomy of leaves of Morus alba L. (Moraceae) cultivars from Poland

The article presents results of research on the micromorphology and anatomy of leaves of Morus alba cultivars. Mature leaves from generative shoots were collected in the Cytadela Park in Poznań and from trees planted along streets in different towns in the Wielkopolska region. A light microscope and a scanning electron microscope were used for observations. There were significant differences between the adaxial and abaxial epidermis. The idioblasts are found on the adaxial surface and stomata on the abaxial surface. Stomata can be classified into two types small and large. Several types of trichomes were recognized on the leaves: straight or hooked, unicellular, glandular capitate, spherical to elliptic stalked. Anatomical investigations revealed that leaves of M. alba cultivars were bifacial and the multi-layered mesophyll was diversified into palisade parenchyma and spongy palisade-like parenchyma. The research findings may be used for the identification of M. alba cultivars, while the epicuticular traits may be useful for the identification and classification of fragments of fossil leaves. The article includes descriptions and illustrations of several new quantitative and qualitative characters of the petiole and lamina, which have not been published previously and are described for the first time from Poland.