Palyno-Morphological Characteristics as a Systematic Approach in the Identification of Halophytic Poaceae Species from a Saline Environment.

Abstract

Pollen morphology of 12 salt-tolerant grasses (Calamagrostis pseudophragmites, Cenchrus biflorus, Cenchrus ciliaris, Cenchrus pennisetiformis, Cymbopogon jwarancusa, Dactyloctenium aegyptium, Echinochloa colona, Echinochloa crus-galli, Saccharum griffithii, Saccharum ravennae, Saccharum spontaneum, and Urochloa ramosa) from the Salt Range was studied using scanning electron microscopy (SEM) and light microscopy (LM). The main aim was the elucidation of taxonomic significance of pollen morphology, which might be useful for taxonomists in the identification of halophytic Poaceae taxa. The described pollen morphology is a good source of taxonomic characteristics that can help in species and genera differentiation. The investigated variations in the pollen micromorphological features and exploration of new palynological traits support and strengthen the systematics of Poaceae. The pollen shape of all studied species was sub-spheroidal, and exine ornamentation includes microechinate-areolate (11 spp.) and microechinate (1 spp.). Two types of pollen apertures were reported, i.e., monoporate (11 spp.) and diporate (Cenchrus pennisetiformis). The annulus was found in all species while operculum was observed only in three species. The univariate and multivariate analyses were used to analyze the quantitative data. The highest pollen viability values (%) depicted the adaptability of Poaceae taxa in the salt region. Overall, the pollen characteristics in polar and equatorial view, apertures, annulus, operculum, and surface ornamentation of pollen grains of the family Poaceae are of great taxonomic significance for the species identification.