Foliar epidermal micromorphology and its taxonomic implication of some Myrtaceae Juss. taxa

Abstract

The plants of Myrtaceae family show great economic potential for its medicinal properties, food and ecological importance. So, the leaf micromorphological characters of 26 cultivated species represent 15 genera belonging to family Myrtaceae, collected from Mazhar garden, Al-Bragil, Giza, Egypt, were examined using light and scanning electron microscope to evaluate these characters in taxa identification and delimitation. In this study, nine stomatal types were recognized; anomocytic, anisocytic, cyclocytic, staurocytic, paracytic, brachyparacytic, pericytic, diacytic and actinocytic, while paracytic is the most common. These types occurring were either hypostomatic or amphistomatic exclusively (homostomatic) or in combination (heterostomatic). For each species, the epidermal cell shape, type of anticlinal wall, shape and number of overlying cells associated with the secretory cavities, as well as presence or absence of unicellular trichomes were also recorded. The results showed the presence of abnormal giant stomata in ten taxa only which were considered more diagnostic. Eight sculpturing patterns were scored in these studied taxa; reticulate, ruminate, rugose, sclariform-reticulate, tuberculate, reticulate-foveate, colliculate and pusticulate. Other diagnostic features were recognized viz. The shape of periclinal walls of the epidermal cells, epicuticular wax, shape and level of stomatal aperture. An identification key based on the leaf micromorphological characters is provided to distinguish the genera and species.