XVI International Botanical Congess

Several characters of monocot pollen and anthers (micorporogenesis type, tapetum type and inaperturate pollen) are reviewed in relation to recent phylogentic concepts of the group. Successive microsporogenesis predominates in the monocotyledons although the simultaneous type is of systematic significance within some order s, e.g. Dioscoreales, Asparagales, and Poales. The first-branching monocotyledon, Acorus, has a secretory tapetum but among other early-braching taxa, most Alismatales (except Tofieldia) are plasmodial. Pandanales, Diocoreales, Liliales, and Asparagales are almost uniformly secretory. The tapetum is more diverse withing the commelinoid clade. Inaperturate pollen (either >functionally momoaperturate= or ominaperturate=) occurs in every major monocot group. It predominates in Alismatales and Zingiberales, and is a synapomorphy for some Liliales and Asparagales. Thus, pollen and anther character s are highly informative in higher-level systematics of monocotyledons. We are therefore extending this approach to the putative monocot sister groups among >primitive= dicotyledons.