LEAF EPIDERMAL MICROMORPHOLOGY IN TANACETUM (ASTERACEAE) FROM IRANIAN SPECIES: TAXONOMIC IMPLICATIONS

چکیده مقاله

Leaf epidermal micromorphology was investigated in nine Tanacetum species from Iran to assess their taxonomic relevance. Both light microscopy (LM) and scanning electron microscopy (SEM) were used to examine qualitative and quantitative characters, including stomatal type, epidermal cell shape, trichome structure, and stomatal measurements. Three stomatal types, namely anomocytic, paracytic, and anisocytic, were observed among the studied taxa, with paracytic and anisocytic stomata restricted to a subset of species. Noticeable variation was also found in stomatal size and stomatal index, as well as in epidermal cell morphology, which ranged from irregular forms in most species to polygonal cells in T. balsamita. SEM observations provided clearer details of epidermal surface features and revealed the presence of both glandular and non-glandular trichomes. The combination of these characters allowed differentiation among closely related species and highlighted patterns that are not always evident at the macromorphological level. The results indicate that micromorphological traits of the leaf epidermis can provide useful complementary evidence for species delimitation in Tanacetum. © 2026, Research Institute of Forests and Rangelands of Iran. All rights reserved.