Pollen morphology of the tribes Gnaphalieae and Calenduleae, and their systematic contributions

The Gnaphalieae, is moderately a large tribe within Asteraceae, comprising approximately ۱۷۸ genera and ۲,۱۰۲ species, predominantly distributed in temperate regions. This study aims to identify and describe pollen types in the Gnaphalieae and Calenduleae, as well as to investigate the relationship among their taxa based on pollen data. The pollen micromorphology of ۱۰ species representing eight genera from these tribes in Iran was examined using light and scanning electron microscopy. The present study showed a noticeable variation in palynological data among Gnaphalieae and Calenduleae studied species. Three pollen types in Calendula, Lasiopogon, and Helichrysum, were identified here among the studied taxa. Clustering and ordination analyses, including WARD tree, PCA and PCoA plots, revealed that, Calenduleae can be distinguished from Gnaphalieae using its tetra-zonocolporate pollen grains and pollen features such as polar axis length, spines height and the distance between spines. Furthermore, palynological data analysis revealed the significance of pollen features in identifying and delimiting species within Gnaphalieae. Similarities in pollen shape and exine ornamentation suggested that, Calenduleae may represent a sister group to Gnaphalieae. The results also indicated that, pollen morphology is a reliable tool for species delimitation within these two tribes.

کلیدواژه ها:

Calenduleae ، Compositae ، Gnaphalieae ، LM ، pollen micromorphology ، SEM