Pollen Morphology and Generic Delimitation of the Polygonaceae in Egypt

POLLEN grains of 18 species representing seven genera (Atraphaxis, Calligonum, Oxygonum, Emex, Periscaria, Polygonum and Rumex) of Polygonaceae Juss. (Subfamily, Polygonoideae) in Egypt were investigated using light microscopy (LM) and scanning electron microscopy (SEM) to evaluate the taxonomic value of micro-morphological characters of pollen grains in order to differentiate between the genera and species. The study showed that pollen grains are radially symmetrical, isopolar, oblate-spheroidal, spheroidal, subprolate to prolate, with ambtrilobed or circular, tricolporoidate, tricolporate, rarely tetracolporate and pantopolyporate. Tectum is striato-reticulate to reticulate, coarse reticulate with double bacula in muri and pilatelumine, rugulo-reticulate, microechinate-foveolate, and microgranulate-perforate Based on these characters, five groups of pollen types are recognized. The results indicate that pollen morphology characters of shape, aperture and exine ornamentation are useful in generic delimitation. A key for the separation of the different pollen types is provided.