The holly family has an ancient Australian lineage

By Australian Geographic 12 March 2019
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Holly is as Australian as the old man banksia.

WHEN YOU THINK of the holly plant, you probably think of the ultimate European Christmas: snow, carols and a decorated tree. But like mistletoe, of which Australia is home to more than 90 species, holly has an ancient Australian lineage, one that rivals its European descendants.

In 2001, Melbourne University palaeobotanist Anne-Marie Tosolini collected holly leaves fossilised in Antarctica that were over 50 million years old. This dates back to a time when Antarctica was attached to Australia’s southern end, forming the ancient supercontinent known as Gondwana.

But this wasn’t the oldest holly fossil known to science. Rather, the oldest came from Victoria, at around 90-94 million years old, making it the oldest holly fossil pollen ever discovered.

This, according to Anne-Marie, says a lot about the ancient migration of holly and its Australian origins. “What’s amazing is that it appeared here and spread across the whole world, and many of these other early flowering plants didn’t do that,” she says.

Tasmanian mountain pepper (Tasmannia lanceolata), another flowering plant that, like holly, has an ancient presence in Australia, only moved across Gondwana. “It’s a really big survivor and must have had a great reproductive strategy making it good at dispersal,” Anne-Marie says.

The explanation for this lies in the way ancient holly was pollinated. “Today, holly is pollinated by insects, but back then it was likely pollinated by wind, which is why the pollen is very abundant in the fossil record,” Anne-Marie explained.

“Looking at the fossilised pollen, the oldest is from Australia, then from Africa, then it spread north up into Asia and Europe.”

Australia is now home to just one species of holly (Ilex arnhemensis), one subspecies in Arnhem Land in the Northern Territory, and second subspecies in the Cape York Peninsula in far north Queensland.

“In Australia, today, holly live in humid conditions. However, the family does have a wide range and they’re not just tropical, they can spread into cold temperatures as well,” Anne-Marie says, but the fossil record suggests they loved the humid weather.

“We know from fossils during the Early to Late Cretaceous Period that it was very warm and there wasn’t much ice in Antarctica. Carbon dioxide was plentiful, and so they would have thrived.”

For such a successful plant, the fact that their Australian origins is relatively unrecognised is disappointing. “More well-known are the Proteaceae and Antarctic beech. They formed the big forests, so they get more recognition, but holly is even older than those plants.”