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Keywords:

  • Artemisiinae;
  • Compositae;
  • Elachanthemum;
  • exine ornamentation;
  • molecular systematics;
  • pollen type;
  • Stilpnolepis

A morphometrical study of pollen grains using scanning electron microscopy was performed in seven genera belonging to subtribe Artemisiinae (Anthemideae). Forty-six populations representing 40 species were considered, mainly from the genus Ajania (31 populations studied of 25 species). This work also includes observations on the genera Brachanthemum, Cancrinia, Crossostephium, Dendranthema, Elachanthemum, Hippolytia, Kaschgaria, Poljakovia and Stilpnolepis. Most data presented here constitute the first pollen observation for some species and genera (Cancrinia and Poljakovia). Two different pollen exine ornamentations are confirmed for the tribe, Anthemis-type (echinate) and Artemisia-type (microechinate), a result consistent with previous studies. The Artemisia-type is exclusive to the subtribe, whereas the Anthemis-type is found present outside Artemisiinae, suggesting that it may represent the ancestral character state for the group. These pollen types appear to be clearly differentiated on the basis of their size and exine ornamentation. Their phylogenetic distribution in Artemisiinae also generally segregates them: the Anthemis-type is found in Dendranthema and allied genera, whereas the Artemisia-type occurs in Artemisia and closely related genera. However, we found some very rare exceptions to this trend (e.g. Ajania junnanica, Elachanthemum and Stilpnolepis), the possible origins of which are discussed. © 2009 The Linnean Society of London, Botanical Journal of the Linnean Society, 2009, 161, 171–189.