Palynological study of some species of Anthemis genus and its systematic implications

To clarify taxonomic complexity within the Anthemis species, pollen grains of ۱۹ species belonging to three sections of the genus Anthemis sensu strictoand two species of the genus Cota from Iran were examined by using scanning electron microscopy. The pollen grains morphological characteristics are provided for this genus in detail. Pollen grains were trizonocolporate and echinate. The pollen grains shape was prolate and spheroidal with the mean polar axes ۲۰–۳۵ μm and the mean equatorial diameter ۲۰.۳–۲۶.۵ μm. Among the studied taxa, A.microcephala showed the smallest pollen grains, and A. odontostephana possessed the largest ones. The spines were commonly conical with a broad basis, ornamentation within spines was generally rugulate-perforate. Thirteen pollen quantitative and qualitative characters have been analysed statistically by employed UPGMA, PCA and MDS in PAST software. Numerical analysis showed that, features as pollen shape, exine ornamentation, spine length and density were valuable characters for separating the examined taxa. In the resulting clusters, three groups within the investigated species have been recognized. The results derived from the present study, therefore, proved to be concomitant with the previous study on taxonomic infrageneric classification. The palynological evidences confirmed the sectional divisions, and revealed that, A. brachystephana and A. lorestanica in A. sect. Anthemis, have close relationship with A. odontostephana. The palynological characters of sect. Anthemis were similar to Tripleurospermum and Cota. The analysis of the palynological data confirmed the conventional taxonomic classification of the genus Anthemis rather than the phylogenetic classification of the genus.    

Keywords:

Asteraceae , Chamomile , Cota , micromorphology , pollen