Abstract: Knowing the interspecific and intraspecific differences of Mentha species is not easy, this is due to the polymorphism and variations in morphology and anatomy characteristics. Because of lack of local studies, it was necessary to taxonomically highlight some local Mentha species, so the aim of this research was to conduct a comparative study of the qualitative and quantitative variations of three local species of Mentha, to find out the distinctive and differentiating taxonomic characteristics for each species. Biometric measurements were taken to cover all stages of the plant's morphological development including flowering and fruiting. The studied traits included 39 qualitative characteristics and 38 quantitative characteristics. The three studied Mentha species were identified as: Mentha longifolia, Mentha piperita, and Mentha spicata. The studied species showed morphological and anatomical differences, for instance, the stem was hairy in Mentha longifolia and glabrous in the other two species, as well the leaves were velvet on both sides in Mentha longifolia and glabrous in the other two species with the exception of some few and short micro hairs on the margin and the apex of the leaf in Mentha piperita, and the leaves were petioled in Mentha piperita and either sessile or sub sessile in the other two species, Mentha longifolia was unique in the presence of hairs on the corolla, calyx, and flower pedicle. As for the quantitative characteristics, Mentha spicata possessed the largest diameter of peltate glandular trichome of 77.55 micrometer, and the largest length of fruity spike of 11.03 cm. The results indicated the variation of the studied species in a number of morphological and anatomical characteristics such as; the shape and dimensions of leaves and inflorescences, dimensions of the hairs and glandular trichomes, shape of pollen grains, length of polar and equatorial axis. Key words: Mentha longifolia, Mentha piperita, Mentha spicata, Qualitative characteristics, Quantitative characteristics.
Abdel Aleem Bello (Fri,) studied this question.