Trichome Diversity and Foliar Epidermal Micromorphology in Systematics of Wild Brassicaceous Taxa

The present study investigated the foliar micromorphological characteristics of Brassicaceous taxa from Dera Ismail Khan, Khyber Pakhtunkhwa, Pakistan, highlighting leaf epidermal structure, stomata, and trichomes. Twenty species were collected, dried, and examined under a light microscope to identify diagnostic taxonomic characters. Both qualitative and quantitative features, foliar micromorphological characteristics were analyzed. Epidermal cells were rectangular, irregular, or polygonal and exhibited four anticlinal wall patterns. Stomata were anisocytic in all species except Nasturtium officinale , which possessed staurocytic stomata with round, elliptical, or broadly elliptical guard cells. Fourteen species possessed trichomes, whereas six were glabrous. The trichome data included stellate, dendroid, Y ‐shaped, T ‐shaped, and simple hairs. The minimum and maximum epidermal cell lengths were recorded in Diplotaxis acris (25 ± 2.5 μm) and Sisymbrium erysimoides (160.4 ± 0.72 μm), while the minimum and maximum cell widths were recorded in Diplotaxis acris (16.25 ± 1.25 μm) and Raphanus raphanistrum (87.5 ± 2.5 μm), respectively. The stomatal index ranged from 14.28% in Draba oreades to 66.66% in Arabis pterosperma . The smallest stomata were observed in Lepidium sativum (20–20.83 μm), whereas the largest occurred in Arabis pterosperma (36.25–36.66 μm). Trichome length varied from 170 ± 2.5 μm in Lepidium apetalum to 813.75 ± 1.25 μm in Diplotaxis acris . Cluster analysis separated the taxa into two major groups C1 and C2, indicating phylogenetic affinities. These findings demonstrate the taxonomic significance of foliar epidermal features and their value in species identification, systematic classification, conservation, and phenetic studies of Brassicaceae.