Taxonomic Significance of Leaf Epidermis, Lamina and Venation of Selected Hoya R.Br. Species in Peninsular Malaysia

This study focused on five species of Hoya, namely H. mcgregorii Schltr, H. ischnopus Schltr., H. pubicalyx Merr., H. flavescens Schltr and H. micrantha Hook.f. The objective of this study was to list common, variations and diagnostics characteristics of the anatomical and micromorphological characteristics of the veins, lamina and epidermis of the Hoya species studied and to construct a dichotomous key for species identification based on the characteristics obtained. Methods applied in this anatomical study involved sample preservation with AA solution, sliding microtome sections, leaf epidermal sections, leaf clearing and observation under a light microscope. The study of leaf micromorphological characteristics involved critical drying point, gold plating and observation under a scanning electron microscope. The results of this study showed that there are similarities and differences between the studied species. Common features observed in this study are the presence of latex, the layer and size of epidermal cells, the anticlinal wall pattern of epidermal cells and the type of wax on the leaf surface. The variation characteristics observed were leaf margins and lamina, stomatal index, type of stomata and trichomes that present in species studied. Several diagnostic features were observed in certain species. A dichotomous key for species identification has been constructed from the leaf anatomy and micromorphology characteristics found in this study, which then has taxonomic value.