Leaf micromorphological adaptations of resurrection ferns in Northern Pakistan

The resurrection plant species, termed desiccation-tolerant plants have evolved remarkable ability to withstand extreme dehydration and rapid rehydration of vegetative tissue without damage. Pteridophytes include almost 70 desiccation tolerant species, and there is limited information of vegetative desiccation tolerance in ferns. A field examination of the representatives of the ferns flora of the Northern Pakistan disclosed 5 ferns species belonging to 2 genera with foliage which can revive after dehydration. These species are Asplenium dalhousiae, Asplenium ceterach, Cheilanthes acrostica, Cheilanthes bicolor, and Cheilanthes nitidula. We undertook a comprehensive leaf micromorphological investigation in all the five resurrection fern species. The study were accomplished using light microscopy (LM) and scanning electron microscopy (SEM). The detailed investigation of adaxial and abaxial leaf surfaces revealed species specific variation in the size and number of epidermal cells, size of stomata, and stomatal pore, stomatal density, and stomatal index and other foliar micromorphological features. In all studied species, adaxial surface lack stomata, i.e., all species are hypostomatic, stomata is polocytic, and epidermal cells shape in all species on both surface is similar, and are irregular shaped. The quantified leaf micromorphological traits are discussed in order to detect their possible role in the desiccation tolerance of resurrection fern species.