Abstract: Since 1998, research into more than 470 plant species from some 65 families, found growing in a unique protected area of Irano-Torany, has examined diverse aspects of their anatomical and structural features and has studied the ecological implications of these finding for each species. The present paper, as a part of this research, focuses on the stomatal characters of 326 species from 36 families of dicotyledons, the majority of which are herbaceous species. The stomatal density, guard cell lengths on the adaxial and abaxial leaf epidermis and the stomatal type in each family is described and the relationship between stomatal density and guard cell size is reviewed. The stomatal characteristics presented here are a valuable research resource, allowing; I) the identification of basic stomatal types in these plants, II) the facilitation of their taxonomic classification and III) constitution of a baseline data set against which to monitor and evaluate environmental changes at these sites of international conservation interest.