From a biostratigraphic study of the distribution of dispersed fossil spores and pollen in the Lower Tertiary sediments of southern Australia, six zonules have been recognised. These have been correlated with the succession of foraminiferal zones in the marine sequence and thus their relative stratigraphic position is well known. The zonules can be correlated over wide areas of southern Australia and are therefore of more than local correlative value. They provide the criteria for the recognition and correlation of both geological and palaeobotanical events. In the section on stratigraphy and correlation, the nomenclature of the Lower Tertiary sediments in South Australia has been reviewed and revised where necessary. In addition, several un-named units have received formal stratigraphic names. These are the Poelpena, Wanilla and Wilkatana Formations, the Renmark Beds, and the Burrungle Member of the Knight Formation. The study has highlighted two important time stratigraphic boundaries. One, that lies between the Upper Cretaceous and Lower Tertiary, can be defined arbitrarily on microfloral assemblages occurring in essentially a non-marine or marginal marine sequence. The beginning of Tertiary sedimentation in Southern Australia is marked by the appearance of spores and pollen characteristic of the Gambierina edwardsii Zonule and younger sediments. These include pollen from the genera Beaupreaidites, Echiperiporites and Proteacidites. The Tertiary microfloras are distinct from those of the upper Cretaceous, and the boundary between the two approximates closely a disconformity recognised on geophysical evidence. The other boundary, between the Paleocene and Eocene, is represented by a hiatus. The change from Paleocene to middle Eocene sediments is accompanied by a major floral change. Particularly striking is the appearance in large numbers of several new Nothofagidites species, together with an increase of more than 40% new species. At this time too, more than 30% of the species present in the youngest Paleocene (or perhaps earliest Eocene) became extinct. Neither faunas nor microfloras characteristic of the Lower Eocene have been recognised. In the systematic section, two new genera, Gambierina and Lakulangipollis, have been proposed, and about sixty six new species described. Of these new types, more than twenty five are members of the genus Proteacidites, and it is during the Lower Tertiary that this genus reaches its maximum diversity. The final section briefly highlights the differences between the Australasian fossil floras and those of the rest of the world during this time. A broad correlation exists between the microfloras of Australia and New Zealand. Both of these regions show similar development of the Nothofague group over a similar time interval. The genus Proteacidites in New Zealand microfloras apparently does not reach as great a diversity as it does in southern Australia.