Pollen morphology of some Nepeta L. species in NW Iran

The genus Nepeta L., with approximately 300 species, is one of the largest genera in the tribe Mentheae, subtribe Nepetinae of the Lamiaceae family. In the present work, pollen morphology of eight species of Nepeta was examined using scanning electron microscopy. The results indicated that the majority of the studied species were characterized by monad, hexazonocolpate, isopolar, heterobrochate, and prolate pollen grains. It was also revealed that there were some differences in pollen characters among the studied taxa. Hence, they could be divided into three major groups based on exine ornamentation. It is worthy of mention that the species pollen characters appear to correlate with the Rechiger (1982) subgeneric classification of Nepeta. However, due to different pollen attributes, it is suggested that Nepeta haussknechtii could be transferred to a new section. Pollen morphology of N. crassifolia, N. haussknechtii, N. speciosa and N. amoena was described for the first time.