Fossil clue to Kiwi Christmas trees

FOSSILS found near St Helens on Tasmania’s East Coast have provided clues to the origins of the New Zealand Christmas tree.

University of Adelaide research has found ancestors of the Pohutukawa tree may have originated in Australia.

The fossils come from the middle of the Cenozoic era — about 25 million years ago — according to the research published in the American Journal of Botany.

The Rata is the most famous Pohutukawa tree and is of particular significance to the Maori culture. It also grows in Hawaii, Papua New Guinea, New Caledonia, Tahiti and on sub-Antarctic islands.

Researcher Myall Tarran said that despite the species’ highly effective seed dispersal biology, it is not found in Australia.

“Australia is the only major vegetated landmass in the Southern Hemisphere where the species does not occur today,” said Mr Tarran, a PhD candidate at the University of Adelaides’s School of Biological Sciences.

The Tasmanian fossils showed the genus did occur in Australia but had since become extinct.

He said the fossils provided strong evidence the diversity of Rata first evolved in Australia and may have had an Australian origin.

“The lightweight and robust seeds are able to be blown by light winds, survive freezing temperatures and up to 30 days in salt water and still germinate,” Mr Tarran said.

“The question still remains as to why they became extinct in Australia.”