Comparative study of leaf anatomy and essential oils of the hybrid Mentha X villoso-nervata and its parental species M. longifolia and M. spicata.

摘要

Following a study of material of all 3 taxa collected from Landada, northern Greece, the leaves of the hybrid Mentha X villoso-nervata are covered with non-glandular trichomes of intermediate length between those of its parental taxa M. longifolia and M. spicata. Glandular trichomes producing essential oils are more numerous on the lower leaf surface than on the upper one in all three mints. Their number per mm2 is higher in M. spicata and it decreased in M. longifolia and M. X villoso-nervata. Stomata are also more numerous on the lower leaf surface of the three taxa, with M. longifolia predominating. The leaf lamina of M. X villoso-nervata is～83% thicker than that of M. longifolia and～9% thicker than that of M. spicata. The number of chloroplasts per mm2 of mesophyll section (leaf cross section) is higher in M. X villoso-nervata. In leaf paradermal sections, the sizes of the epidermal, palisade, and spongy parenchyma cells of M. X villoso-nervata have intermediate values between those of itsparental species M. longifolia and M. spicata. M. X villoso-nervata leaves are the lowest in essential oil content. As concerns the essential oil composition, the hybrid resembles one parent, M. longifolia, in the derivatives of piperitenone and piperitone, and the other parent, M. spicata, in the high amount of limonene. It differs, however, from its parental species in that it contains a higher amount of germacrene D.