Gondwana Plant Families

Araucariaceae

This Gondwanan family includes three genera: Araucaria, of which the best known species is Araucaria araucana, the Monkey Puzzle Tree which can live for 1,800 years and grow to a height of more than 60 metres; Agathis, of which the best-known is the Kauri of New Zealand, which was logged almost to extinction; and Wollemia, the Wollemi Pine, discovered in a gorge in the Blue Mountains in 1994 and already extinct in the wild. Fossils resembling Wollemia and possibly related to it are widespread in Australia, New Zealand and Antarctica, but Wollemia nobilis is the sole survivor of its genus and is often described as a living fossil.

Podocarpaceae

This family is a classic member of the Antarctic flora, the greatest number of representatives being found in Australia, New Caledonia and New Zealand, and to a lesser extent in Malesia and the Andean regions of South America. The family contains 19 genera, of which the largest with 80 to 100 species is Podocarpus, followed by Dacrydium with 21. The characteristic of the family is that the members are gymnosperms and do not flower, bearing instead a seed on the end of a twig surrounded by a fleshy covering called an epimatium.

Nothofagaceae

This family has only one genus, Nothofagus, and the genus about 36 species scattered through higher elevations of southern South America (10), Australia (3), New Zealand (4), New Caledonia (5), and the mountains of New Guinea (14). Fossils have been found in Antartica. Its distribution in isolated pockets at cooler high latitudes in otherwise warmer regions is considered to provide evidence of a wider distribution affected by climate change.

Proteaceae

Proteaceous plants are to be found on every remnant of Gondwana. The family and its sub-families are thought to have diversified long before the break-up of Gondwana, so it is assumed that proteaceous species developed more than 90 mya. Part of the evidence is the amount of proteaceous pollen to be found in New Zealand coal deposits dating from the Cretaceous, 145mya to 64mya. New evidence however is complicating the picture as many species have developed rather more recently and are thought to have been dispersed across ever-widening ocean gaps, possibly via now-submerged island chains. None of the Proteaceae is adapted to exploit local mycorrhiza; instead they produce proteoid root mats which provide an absorptive surface amid the leaf litter layer, and exude carboxylates that mobilise previously unavailable phoshorus.

Tree-Ferns

The discovery of the fossil fern Glossopteris in Carboniferous and Permian rock in South America, South Africa, India and Antarctica was one of the earliest indications that these now widely separated land masses were once united. Ferns are one of the earliest plant forms to evolve, appearing on earth 365mya. Gondwanan forests all feature a vast array of tree-ferns belonging to two predominant families, the Cyatheaceae and the Dicksoniaceae.