Comparative epidermal morphology of West African species of Jatropha L. (Euphorbiaceae)

Abstract

Leaf epidermal morphology of the eight species of Jatropha found in West Africa has been studied by both light and scanning electron microscopy. The cells of adaxial and abaxial epidermises are usually polygonal with either straight or curved anticlinal walls. Wax occurs in some species in the form of either flakes, particles or plugs, while in others prominent cuticular striations are found which may be parallel or random. Paracytic and brachyparacytic stomata which may be superficial, or sunken with either narrow or wide cuticular rim occur on both surfaces of the abaxial surface only. Stomatal size varies both within and between taxa. Pubescent and glabrous species occur within the genus. Trichomes are either unicellular or uniseriate. The presence of stalked glands on leaf margins is unique to J. gossypiifolia. Evidence is presented to show the close relationship between J. neriifolia and J. atacorenis. Other variable micromorphological characters of the epidermis include cell size, periclinal walls, distribution and density of trichomes. The taxonomic significance of these features in identification and elucidation of species affinity is discussed.