Multivariate characterization of foliar morpho-anatomical traits supporting adaptive trends and taxonomic resolution in halophytic grasses

Abstract

Leaf morphology and epidermal traits of 15 salt-tolerant grasses belonging to 10 genera from the Bahadur Khel Salt Range were examined using a microscopic technique for the first time. Eight qualitative characters (epidermal cell shape, anticlinal wall patterns, type of stomata and trichome, phyllotaxy, leaf base/apex, leaf shape, and margins) and seven quantitative characters (size of epidermal, subsidiary, and guard cells, stomata, stomatal pore, trichome, and stomatal index) were analyzed for both abaxial and adaxial surfaces. All salt-tolerant grasses exhibited paracytic stomata. The maximum stomatal length of 53.65 ± 1.51 and the lowest of 22.35 ± 0.33 were noted. The shape of epidermal long cells varied from regular, wavy, to isodiametric. Saccharum spontaneum showed the longest epidermal cells (91.05 ± 4.53) on the adaxial surface. Thirteen species exhibit sinuate anticlinal wall patterns except Cenchrus ciliaris and Setaria viridis , which show an undulate pattern. Cenchrus pennisetiformis exhibited large subsidiary and guard cells on both surfaces. Five types of trichome were observed: micro-hairs, macro-hairs, hooks, prickles, and papillae. The highest trichome length was exhibited by Cenchrus biflorus (89.35 ± 37.36) on the abaxial surface and by Paspalum distichum (63.2 ± 4.58) on the adaxial surface. Principal component (PCA) and cluster analysis were used to analyze foliar micromorphic data, revealing potential affinities among salt-tolerant grasses. The outcomes of this study explored the significance of foliar epidermal properties in linking ecological adaptations and evolutionary traits that contribute to the taxonomic position of halophytic grasses for identification and categorization.