Palynological data from Australia and New Zealand show marked vegetational changes throughout the Late Cretaceous and Cenozoic in response to climatic changes, fluctuations of the Antarctic ice cap, drifting of the continents and to a lesser extent tectonic activity. New Zealand and New Caledonia separated from Australia and Antarctica about 80 million years ago at which time the New Zealand vegetation had predominantly Austral affinities. Podocarps and southern beeches existed in an environment characterised by long winter nights and low temperatures. As New Zealand moved northeast a gene flow was maintained with Australia by long-distance dispersal of pollen, spores and seeds by wind, water and birds. A similar vegetational history of Nothofagus in Australia, New Zealand and South America can only be explained if the gene pool was similar in each area; this implies continual contact. During the Cenozoic, New Zealand received new taxa, some of which had previously appeared in Australia and some which survived in New Zealand after extinction in Australia. The best examples of this are Acacia which appeared in New Zealand in the Early Pliocene after its Early Miocene appearance in Australia, and Beauprea which became extinct in Australia in the Miocene but still occurred in New Zealand in the Early Pleistocene. Australian and Malayo-Pacific elements in the New Zealand flora became more prominent, as did the endemic element. The New Zealand vegetation was primarily warm-temperate, reaching subtropical in the Early to Middle Miocene and cool-temperate in the Late Miocene and Pliocene. No New Zealand palynofloras can be regarded as tropical since, although Palmae pollen dominates many Late Oligocene and Miocene assemblages, tropical genera such as Mauritia (or Nipa), Anacolosa (Indomalayan), Bombax, Cupania and some genera within the Proteaceae occur only spasmodically, and the abundance of Casuarina and Nothofagus “brassi” beech at this time suggests high humidity, but not necessarily high temperatures. The New Zealand vegetation was greatly modified by Pliocene and Pleistocene glaciations, resulting in the modern unstable disjunct distribution pattern.