Comparative leaf anatomy of Kokoona and Lophopetalum (Celastraceae)

The leaf anatomy of Kokoona and Lophopetalum is described in detail. Separation of the two genera as effectuated by Hou (1963) is supported by differences in vascular anatomy of the distal end of the petiole, which is invariably more complex in Lophopetalum than in Kokoona. Other differential characters (p. ooo) only apply to part of the species of Lophopetalum. As based on leaf anatomy it is impossible to define groups of closely related species within the genera because of a lack of mutual correlation between the different leaf anatomical characters. Lophopetalum in particular shows some striking anatomical features such as a very variable and complex arrangement of vascular tissue in petiole and midrib, complex types of cyclocytic and anisocytic stomata, crystarque cells, and epidermal papillae. Most of these characters occur in part of the genus only. The variability below the species level of characters such as epidermal wall thickness, number of subsidiary cells per stoma, dimension of guard cell pairs, presence or absence of stomata in upper epidermis etc. is reported for some species. Because of the great range of anatomical variation it is impossible to identify species, using leaf anatomical characters only.