Pollen diversity and its systematic significance in the tribe Anthemideae (Asteraceae)

Anthemideae, with over 111 genera and 1800 species, is one of the largest tribes within the Asteraceae family. Some members of this tribe are recognised for their aromatic and medicinal properties. Central Asia, the Mediterranean region and southern Africa are the main distribution centres for this tribe. The taxonomy and subtribal classification of the Anthemideae remain controversial and unresolved. Pollen micromorphology can be a valuable and informative tool for resolving taxonomic problems at the subtribe, genus and species levels. The present study aims to describe the pollen types within a small subset of Anthemideae tribe from Iran and to investigate the relationships among a small set of subtribes, genera and species using palynological data. The pollen micromorphology of 14 species representing 14 genera of Anthemideae was examined using scanning electron microscopy. Consequently, three pollen types – Anthemis, Artemisia and Handelia – were identified among the studied taxa, with the latter being newly described. Using clustering and ordination analyses – unweighted pair group method with arithmetic mean (UPGMA), principal component analysis (PCA) and principal coordinate analysis (PCoA) – the species from the four subtribes – Anthemidinae, Glebionidinae, Handeliinae and Leucantheminae – could, in most cases, be distinguished from each other. However, some incongruences between pollen features and accepted taxonomy were observed among the Artemisiinae species.