Comparative epidermal leaf anatomy of some Brassicaceae with emphasis on its systematic implication

Some epidermal leaf anatomy characteristics such as the absence/of presence trichomes and stomata and trichome types in adaxial and abaxial leaf surfaces within different species, subspecies, varieties, and populations are afforded valuable taxonomic characteristics in their determination. This study aimed to investigate the leaf epidermal characteristics in 72 populations belonging to 46 wild and native Brassicaceae taxa collected from central Iran. The adaxial and abaxial leaf epidermis was examined using light microscopy. Results showed that all studied samples lack crystals in their epidermis. They can be divided into three groups: 1) without trichomes in both adaxial and abaxial leaf surfaces, 2) having trichomes just on the abaxial side (Lepidium sativum and Sisymbrium irio), and 3) trichomes in both adaxial and abaxial surfaces. Two Choriospora species can be separated by their trichomes. C. iberica has glandular trichome, while C. tenella has no trichomes. This study revealed that just epidermal leaf anatomy characters are not sufficient to identify members of the Brassicaceae members, but can be helpful along with other features and may support the systematic value of taxa in this family.