Antarctic Flora

The Antarctic flora is a distinct community of vascular plants which evolved millions of years ago on the supercontinent of Gondwana, and is now found on several separate areas of the Southern Hemisphere, including southern South America, southernmost Africa, New Zealand, Australia and New Caledonia. Based on the similarities in their flora, botanist Ronald Good identified a separate Antarctic Floristic Kingdom that included southern South America, New Zealand, and some southern island groups. Good identified Australia as its own floristic kingdom, and included New Guinea and New Caledonia in the Paleotropical floristic kingdom, because of the influx of tropical Eurasian flora that had mostly supplanted the Antarctic flora.

Millions of years ago, Antarctica was warmer and much wetter, and supported the Antarctic flora, including forests of podocarps and southern beech. Antarctica was also part of the ancient supercontinent of Gondwana, which gradually broke up by continental drift starting 110 million years ago. The separation of South America from Antarctica 30-35 million years ago allowed the Antarctic Circumpolar Current to form, which isolated Antarctica climatically and caused it to become much colder. The Antarctic flora subsequently died out in Antarctica, but is still an important component of the flora of southern Neotropic (South America) and Australasia, which were also former parts of Gondwana.

Some genera which originated in Antarctic Flora are still recognized as major components of New Caledonia, Tasmania, Madagascar, India, New Zealand, and southern South America.

South America, Madagascar, Africa, India, Macaronesia, Australia, New Zealand, and Antarctica were all part of the supercontinent Gondwana, which started to break up in the early Cretaceous period (135-65 million years ago). India was the first to break away, followed by Africa, and then New Zealand, which started to drift north. By the end of the Cretaceous, South America and Australia were still joined to Antarctica. Paleontologist Gilbert Brenner identified the emergence of a distinct southern Gondwanan flora by the late Cretaceous period in the cooler and humid southern hemisphere regions of Australia, southern South America, southern Africa, Antarctica, and New Zealand; it most resembled the flora of modern-day southern New Zealand. A drier northern Gondwanan flora had developed in northern South America and northern Africa.

Africa and India drifted north into the tropical latitudes, became hotter and drier, and ultimately connected with the Eurasian continent, and today the flora of Africa and India have few remnants of the Antarctic flora. Australia drifted north and became drier as well; the humid Antarctic flora retreated to the east coast and Tasmania, while the rest of Australia became dominated by Acacia, Eucalyptus, and Casuarina, as well as xeric shrubs and grasses. Humans arrived in Australia 50-60,000 years ago, and used fire to reshape the vegetation of the continent; as a result, the Antarctic flora, also known as the Rainforest flora in Australia, retreated to a few isolated areas composing less than 2% of Australia's land area.

The woody plants of the Antarctic flora include conifers in the families Podocarpaceae, Araucariaceae and the subfamily Callitroideae of Cupressaceae, and angiosperms such as the families Proteaceae, Griseliniaceae, Cunoniaceae, Atherospermataceae, and Winteraceae, and genera like southern beech (Nothofagus) and fuchsia (Fuchsia). Many other families of flowering plants and ferns, including the tree fern Dicksonia, are characteristic of the Antarctic flora.