Comparative anatomical and morphological studies on leaves of some Citrus species and their systematic implications

In this study, leaf micromorphological features of 42 accessions of 12 species of the genus Citrus were assessed through light microscopy and scanning electron microscopy, to evaluate phylogenetically significant characters that delineate species. Morphometrical analyses were carried out using the leaf anatomical and micromorphological characters of at least five samples collected from different localities. Some leaflet anatomical traits (cuticle ornamentation, cyclocytic and tetracytic stomata, isobilateral mesophyll arrangement, number of palisade layers, shape of the midrib, sheath around vascular tissue) clearly support various clades defined by previous DNA-based phylogenetic work. Anatomical features of C. limetta and C. aurantifolia were identical, thus supporting the synonimisation of these two species. Leaf anatomy and morphology in the studied taxa reveal many characters high value for infrageneric classification of Citrus. This work provides useful background for further molecular and anatomical studies of Citrus.