One of the main features of Sydenham Botanic Park being developed is a Gondwana theme. New Zealand’s flora is dominated by Gondwanan plants, comprising historically of forests, most famously the giant kauri (by volume the largest trees in the world).
Gondwana is the name given to the more southerly of two ancient supercontinents which were part of the Pangaea supercontinent that existed approximately 600 million years ago.
180-220 million years ago Pangaea broke up into Laurasia and Gondwana due to movement under the earths crust caused by heat. 150 million years ago Gondwana started breaking up into todays southern continents, including Antarctica, South America, Africa, Madagascar and the Australian continent, as well as the Arabian Peninsula and the Indian subcontinent, which have now moved entirely into the Northern Hemisphere.
The landmass of New Zealand is part of the Zealandia continental fragment which split off Australia 60-80 million years ago and sank into the Pacific Ocean. New Zealand’s biodiversity is one of the most varied and unique on earth due to its long isolation from other continental landmasses.
A good book exploring New Zealand’s historical biogeography is Ghosts of Gondwana- The history of life in New Zealand by George Gibbs.