The Wollemi pine, one of the world's rarest and oldest trees, is listed as a critically endangered species in New South Wales having been thought extinct until as recently as 1994.

The Department of Foreign Affairs and Trade approached the Australian National Botanic Gardens horticulture manager Phil Hurle, who said the major hurdle was to be able to pass Canada's strict quarantine laws.

"There were some import issues of course. Anything imported into Canada needs to be bare rooted," Mr Hurle said.

"That was a huge problem for us. We couldn't send over a 2.3 metre tree, it just wouldn't have survived."

The Botanic Gardens worked with Australia's agriculture department, DFAT and the Canadian government to begin passing quarantine laws.

Mr Hurle said the tree was potted in "pasteurised media", a potting mix 'cooked' in a steaming trolley at 65 degrees celsius to kill any pathogens or hitchhikers.

Then the tree was sprayed down with insecticide.

"Then the challenge was to send a tree over to Canada by plane and not have it damaged," Mr Hurle said.

The Wollemia was travelling in December, winter in Canada, with temperatures as low as minus 25 degrees.  It had to be transported in a box lined with foam, then freighted on its side.

It went on the back of a ute from Canberra to Sydney, flying direct to Vancouver for free thanks to Qantas before flying to Montreal and being trucked from there to the capital, Ottawa.

"It's never been done before,

sending a tree of that size," Mr Hurle said.

Canadian governor general Julie Payette was presented the pine by Australia's high commissioner Natasha Smith on Saturday morning, Canberra time.

The pine can be expected to grow as tall as 40 metres and to live for around 500 years.