Uredinia and urediniospores of six Puccinia species growing on Poaceae in southwestern Saudi Arabia were morphologically compared by light and scanning electron microscopy (SEM). Puccinia cenchri, P. fragosoana and P. isiacae were recorded for the first time in Saudi Arabia. Many differences between uredinia and urediniospores of studied Puccinia species were recorded. These differences are not related to host plant but may be due to the species of Puccinia itself. Observations by SEM led to more information in distinguishing between these Puccinia species particularly the presence of paraphyses and density and length of spines.

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Light microscopy, scanning and transmission electron microscopy were used to study the morphology and the ultrastructure of the pollen grains of Withania somnifera (L.) Dunal. Light microscopic examination revealed that the pollen grain is tri-or tetrazonocoplate, approximately as long as broad measuring 29-µm. Scanning electron microscopic observation showed that surface sculpture is scarbate-granulate. Ultrathin sections as examined by transmission electron microscope showed that the pollen contained numerous starch grains, liped drops, endoplasmic reticulum and vesicles of dicotysomes. Two layers of pollen wall were also distinguished; the outer wall (exine divided into ektexine and enexine as well as an inner layer (intine). The nutritive values of Withania pollen were discussed. The importance of studying the ultrastructure of pollen grains as a new tool in plant taxonomy was also discussed.