Germinal Apertural Formation in Pollen

Summary Evolutionary proposals involving pollen grain characters have treated germinal apertures as though they were formed by one universal process and hence derivable from a common type. A review of published data on apertural formation for pollen of Silene, Tradescantia , and Nelumbo and original information for Epilobium indicates that there are several possibly distinct apertural induction processes. It would seem to be an oversimplification and perhaps misleading to ignore apertural genesis in interpretations involving relationships between taxa.