Pollen Grains and Caryopsis Features of Selected Poaceae species and Their Taxonomic Significance

Abstract

Pollen grains and caryopsis morphology of seventeen species belongs to seventeen genera, eight tribes and three subfamilies of Poaceae were studied by using light and scanning electron microscopes. Morphological characters of pollen grains and caryopsis coat are very important traits which can be used at taxonomic level. Pollen grains are mostly oblate-spheroidal, spheroidal and prolate-spheroidal while recorded six shapes elliptic, oblong, ovate, broad ovate, obovate and rounded for caryopsis. On the basis of exine ornamentations five distinct pollen types are recognized (verrucate-granulate, areolate-granulate, micro gemmate, micro gemmate-granulate and granulate) and nine different patterns for caryopsis surface coat (reticulate, rugose, scalariform, striate, reticulate -foveate, reticulate-rugose, reticulate-striate, ruminate and striate -favulariate). The size, shape, exine thickening, exine ornamentation, operculum and annulus diameter of pollen grains are very important characteristics for delimiting the species. Palynology do not support the tribal and generic classification, whereas the morphology of caryopsis is crucial for identifying the taxa in the family Poaceae.