Abstract: The outer and inner surfaces of leaf epidermis of three genera (Heminthostachys, Ophioderma, Ophioglossum) in Heminthostachyaceae and Ophioglossaceae were investigated under light and scanning electron microscopes. Their epidermal cells are regular with straight or slightly curved anticlinal walls. The longitudinal axes of stomatal apparatus generally parallel with the long axis of the lamina. Guard cells somewhat sunken. The epidermal features of the three genera are different in the outline of epidermal cells, the degree of curved anticlinal wall of epidermal cells, the distribution and types of stomatal apparatus. These differences contribute evidences for systematics of Ophioglossales.

Key words: Helminthostachyaceae, Ophioglossaceae, Leaf epidermis, Stomatal apparatus