POLLEN MORPHOLOGY OF EGYPTIAN ONONIS L. (FABACEAE) AND ITS TAXONOMIC VALUE

Pollen morphology of 10 taxa of genus Ononis was examined and photographed by SEM to discuss the relationship among them. The taxonomic relationships among taxa were analyzed by means of numerical analysis using UPGMA clustering as well as PCA analysis based on 24 morphological and palynological characters. Shape of pollen, aperture characters and exine sculpturing were described. Based on pollen shape in the equatorial view, four classes were recognized: prolate, subprolate, perprolate and spheroidal– prolate. All the studied pollen grains have tricolporate apertures. The results revealed five patterns of exine sculpturing: reticulate heterobrochate, reticulate-verrucate, punctate, fossulate and microreticulate, the later considered the most dominant type of exine sculpture among the taxa under investigation. Ononis pubescens has the largest pollen grains among the taxa under investigation. Pollen characters proved that it can be useful to differentiate taxa on the sub-sectional level, for example O. diffusa and O. serrata (the representing taxa of sect. Ononis sub-sect. Diffusae) can be easily differentiated from O. mitissima (the representing taxon of sect. Ononis sub-sect. Mitissimae) by shape of pollen grains which is prolate in the former and spheroidal in the latter.