Morpho-histological and quantitative parameters in the characterization of lemon verbena (Aloysia citriodora palau)from Argentina

Lemon verbena, Aloysia citriodora Palau (Verbenaceae)is worldwide used due to the sensorial and medicinal properties of its leaves and essential oil. Micrographic identification of several samples from the most representative growing areas in our country was made in order to define the quality of a typical Argentine lemon verbena. Plant materials were fixed, freehand sectioned and stained with Safranin and Fast Green. Leaves are simples, their blades exhibit anomocytic stomata on the abaxial side, non-glandular and glandular trichomes and dorsiventral mesophyll. The stem, in incipient secondary growth, presents epidermis, angular collenchyma and the vascular bundles which are open collaterally. The morphoanatomical characterization, stomatic index, pallisade ratio and length of stem elements to be used as quantitative parameters of the leaves and stems were determined, in order to contribute to the identification of the plant material.