Leaves of Celastrus paniculatus, C. stylosus, Elaeodendron glaucum, Euonymus japonicus and E. pendulus are essentially hypostomatic, although a few stomata were observed near veins in the upper epidermis of Celastrus paniculatus. Their irregularly orientated stomata show guard cells partly underarched and partly surrounded by a ring of three to eight subsidiary cells. Surface walls of epidermal cells in Euonvmus pendulus show pits whose impressions are also seen in the cuticle.
Rehfous (1914) had suggested that the sunken subsidiary cells of Celastrus europaeus, Catha edulis and Euonymus japonicus and four other species of the genus are formed in an unusual manner from segments of the guard cells. Our studies on the contrary indicate that the subsidiary cells in all our plants, including E. japonicus, are typically perigene.
Mesophyll of all leaves is armed but the form of midrib bundles varies in different species and to some extent in different regions of the same leaf.