How the morphological properties of Mentha longifolia.(L.) Huds. may be affected by geographical differences

With respect to the benefits of medicinal plants for human health and their use as food, they are extensively being researched and planted in different parts of the world including Iran. Among the most important parameters, which may affect the growth and the yield of medicinal plants is their geographical (ecotype) properties. Accordingly, a research work was proposed to investigate the effects of 10 different regions or ecotypes on the morphological properties of pennyroyal [Mentha longifolia. (L.) Huds.] from the Lamiaceae family in one of the Iranian provinces, namely Ilam. According to the geographical characteristics of the experimental province, the longitudes were in the range of 60-65^°, the latitudes varied from 36-37^° and the heights above the sea level were in the range of 860-1410m. The experiment was a completely randomized block design in three replicates and for each plant ecotype, 20 plant samples in three replicates were collected. Different plant morphological properties related to plant stem, leaf, inflorescence, rhizome, and dry weight were determined. Data were subjected to analysis of variance and different plant statistical properties were determined. Using the Ward's method, the cluster analysis of data was also conducted and similar ecotypes were grouped. Data indicated the significant effects of regional (ecotype) differences on plant morphological properties and dry weight. The highest stem length was related to the Alamdar region (90cm), stem diameter and leaf number to Kolm region at 0.76cm and 128, respectively, leaf length to Chenarbashi at 4.07cm, leaf width to Helaesm at 2.83cm, inflorescence number and length to Sarab at 22.10 and 11.63cm, respectively, inflorescence width to Kolm at 1.04cm, rhizome length to Mishkhas at 11.00cm, and rhizome width to Kolm at 1.03cm. The highest dry weights were resulted by Siahkal (260g), Kolm (205g) and Chemarbashi (220g). Interestingly, stem length (22.17), inflorescence width (12.12) and rhizome length (27.11) indicated the least rate of coefficient of variation and had the highest effects on plant growth and yield production. Data indicated how geographical and soil properties (such as organic matter) may affect pennyroyal growth and yield. Such analyses can be used for the selection and the subsequent domestication of wild populations of pennyroyal with the highest efficiency.