Anatomical studies in six taxa of genus Nephrolepis; N . biserrata, N . cordifolia, N .exaltata(i) & (ii), N .biserratavar. furcans and N . undulata were carried out with a view to identify anatomic characters of taxonomic values. Both qualitative and quantitative anatomical studies were carried out. Quantitative data were subjected to descriptive statistical analysis.Anatomical characters studied include venation patterns, trichome types, presence and absence of stomata and values of the stomatal index which are valuable in delimiting the species. The overall results showed overlaps in the quantitative anatomical attributes of the Nephrolepis taxa studied suggesting that they belong to the same genus. Qualitative anatomical attributes that separated the genus into distinct taxa are the presence of simple multicellular glandular trichomes in N .biserrata and simple multicellular non-glandular trichomes in N .exaltata(i) and N .exalta(ii) while N .biserrata var. furcans and N .undulata have simple unicellular non-glandular trichomes andabsence of trichome in N. cordifolia. Presence of anisocytic, diacytic or anomocytic stomata were of diagnostic important in the six taxa.
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.
Guard cells in Ophioglossum petiolatum leaves are initiated by a single division of a stomatal initial with no subsidiary cells being formed. The stomatal initials have few vacuoles, plastids with little starch, and a large nucleus with much heterochromatin and prominent nucleoli.
Young guard cells are similar cytologically to stomatal initials; their common cell walls are thin and traversed by plasmodesmata. Plasmodesmata are also present within guard cell and adjacent epidermal cell walls.
With increasing age, guard cells develop a lenticular thickening in the median portion of the common cell walls, larger vacuoles, and plastids with several starch grains. Numerous microtubules are present near the thickening wall which also has an electron-translucent region between the cell wall and the plasmalemma.
Many dictyosomes and mitochondria are present in the cytoplasm. Older guard cells become more vacuolated, with some of the vacuoles containing fibrillar or dense deposits.
Plastids become very large as a result of storing several large starch grains. In the thickened portion of the cell walls, the middle lamella and some of the adjacent cell wall appear to be degraded during stomatal pore formation.
Mature guard cells are highly vacuolated and have very thick electron-dense cell walls without plasmodesmata. Fluorescence microscopy following aniline blue staining shows that aniline blue positive materials are present around and within the thickened portion of the cell walls, at the junction of guard cells with epidermal cells, and as distinct spots in guard cell and epidermal cell walls during the early stages of ontogeny.
Mature guard cells, however, lack the distinct fluorescent spots, which are interpreted as plasmodesmata, in their walls.
Dryopteris and Polystichum are the 2 complex taxonomic genera of Dryopteridaceae. The comparative foliar epidermal anatomy of 12 species of both genera from Pakistan were studied using standard protocols of light microscopy (LM) and scanning electron microscopy (SEM).
The objective of which was systematic comparison and investigation to elucidate the taxonomic importance of foliar micromorphology, which may be useful to taxonomists for identifying complex Dryopteridaceae taxa.
Principal component analysis and UPGMA clustering analysis were performed to test the validity of leaf anatomical features as method of separating species and genera. The foliar epidermal anatomy described here is a good source of taxonomic characters in both groups that can help genera and species delimitation.
This is the first report on leaf micromorphology in most of these species. Observation of foliar anatomy showed that stomata are only present on the abaxial surface; i.e., leaves of all species are hypostomatic. The shapes of epidermal cells in all studied species are irregular. The anticlinal walls are strongly lobed, irregular wavy and elongated wavy. However, substantial variation in epidermal cell size and other stomatal features were observed on both upper and lower surfaces in all investigated species.
Two types of stomata were observed in all studied species. The presence of polocytic stomata in Dryopteris and staurocytic stomata in Polystichum are the important characters for the segregation of these genera. Elongate elliptic stomatal shape, narrow kidney shaped guard cells and broad elliptic shaped stomatal pores are diagnostic for all five species of Dryopteris selected.
On the other hand, size and number of epidermal cells, lobes per cell, stomatal size, subsidiary cell size, stomatal pore size and stomatal index are the key features for species differentiation in Polystichum.
An identification key was developed in order to apply the foliar anatomical characters in the discrimination of the species studied.
Earlier studies in spore morphology and stomatal properties in some ferns have shown their value in understanding the interrelationships among different species groups.
In the present study the ontogeny and mature structure of spores and stomata of different taxa of Cyatheaceae were traced, and the interrelationship among different genera have been established taking the properties of stomata and spores as parameters of affinities.
The application of palynological and stomatal features has generated a new and better understanding of the interrelationship among the genera concerned, which have followed three distinct lines of diversification from their ancestral condition.
The occurrence of species belonging to the family Adiantaceae is reported from Pokhara, Nepal. The present paper deals with the anatomical details like structure of pinnae, structure of stomata, guard cells, other epidermal cells etc. although several workers has reported about the pteridophytic plants from Nepal but it is the first time to work about the epidermal details of Nepalese fern.
Stomata are generally present on lower side of the leaf and the leaves are hypostomatic in nature. The stomata are surrounded by 2-5 neighbouring cells. Stomata are more or less parallel to the vein.