Pollen morphology of six species of subfamily Stachyoideae (Lamiaceae) in Saudi Arabia

The pollen morphological characters of 6 species belonging to 4 genera of the subfamily Stachyoideae (Lamiaceae) growing naturally in Saudi Arabia were investigated with the aid of light microscope (LM) and scanning electron microscope (SEM), to find new features that might increase knowledge of pollen morphology of the species, and also to help the taxonomic characterization of the Stachyoideae genera. The morphological characters studied were size, shape, tectum surface ornamentation, number and type of the colpi. The study indicated that the average size of the pollen was different among the species since the smallest size was that of Nepeta deflersiana (P = 25.2 ± 2 and E = 15 ± 3) while the largest size was that of Salvia aegyptiaca (P =36.5 ± 2 and E = 30.3 ± 2). Pollen shape is spheroidal to sub-spheroidal or prolate. The fine structure of the exine of pollen was slightly different among investigated species. The number and type of colpi of the pollen in species studied were 6-zonocolpate type except those of N. deflersiana and Otostegia fruticosa ssp. schimperi having 3-zonocolpate.   Key words: Pollen grains, pollen morphology, Lamiaceae, Stachyoideae, Saudi Arabia.