Two new plant species rise like a phoenix from the ashes of WA bushfires, then vanish

 
27 April 2017

published by http://www.abc.net.au


Australia -  An internationally-renowned plant conservation biologist has discovered a new plant species rising from the ashes of two major bushfires near Albany in Western Australia.

University of Western Australia biodiversity professor Stephen Hopper found the previously unknown pennywort while exploring Torndirrup National Park with doctoral student Megan Dilly last November.

A bushfire had torched 616 hectares of the park in November 2015.

Professor Hopper said finding the pennywort growing in the ashes in a small, 100-square-metre area was an exciting moment.

Professor Hopper said the soon-to-be-named species was the second pennywort to be found on dry land anywhere in the world.

Phoenix rises from the ashes

The first was the phoenix pennywort, collected by WA Herbarium identification botanist Robert Davis near Windy Harbour, 20 kilometres south of Northcliffe, in November 2015.

Northcliffe, 350 kilometres south of Perth, was also ravaged by bushfire in February 2015 and the phoenix pennywort was found in the ashes of a burnt Karri forest.

Mr Davis said Professor Hopper's unearthing of another pennywort species a year later was serendipitous.

"It was really quite fascinating," Mr Davis said.

"We had just published the discovery of phoenix when the Albany species came to light.

Pennyworts are perennial herbs that usually grow in, or next to, water.

They belong to the genus Hydrocoytle, while their common name was literally coined from the plant's round leaves which range in size from a five to a fifty-cent piece.

So how did plants usually found in damp habitats raise their heads after bushfires?

Mr Perkins said many plants germinate after fire. They are called fire ephemerals.

Their seeds are long-lived and can lie dormant in the soil for decades.

Professor Hopper said it was a "cunning ploy" for survival by plants.

In the case of the newly-minted pennyworts, the seed may have been carried to areas away from water by the wind.

Fire stimulated their germination by removing competing vegetation and ash enriched the soil with nutrients.

"The plant quickly flowers and drops its seed," Mr Perkins said.

"Once they settle they will stay dormant until the next major fire."

This trait had never been documented in pennyworts before.

"No one expected to find fire ephemeral species in the Hydrocoytle genus," Mr Perkins said.

Double the disbelief

Remarkably, the thrill of finding new flora was experienced again shortly after.

Professor Hopper was stunned to see the Albany pennywort had sprouted in a small section of Two Peoples Bay Nature Reserve, 35 kilometres east of Albany.

A blaze scorched 1,200 hectares of the high-conservation reserve in November 2015.

"The extraordinary thing is, the vegetation that was burnt in 2015 hadn't been burnt for something like 70 or 80 years," Professor Hopper said.

He was astonished the new species had gone undetected for hundreds of years.

"These really are remarkable occurrences," he said.

"Undoubtedly, Noongar people would have encountered the species during their 50,000 years of occupation. But there is no record or oral history that affirms that these days."

A disappearing act


The trio of botanists have all returned to the discovery sites to scour the areas for more signs of the new species, without success.

Mr Perkins said fire ephemerals commonly vanish without a trace.

"If you don't watch them in that window, they're gone," he said.

"It's very unusual to see this group of plants."

Mr Perkins has studied the Albany pennywort specimens and said the species was "on the verge" of being formally described.

The research is expected to be published in the next few months.

Professor Hopper, who has been involved with naming 300 plant species in WA's south-west, said the latest additions to science highlight the region's enormous biodiversity.

"It's just a gold mine for botanical discovery," he said.

South-west WA is one of the world's 35 internationally recognised biodiversity hotspots and Professor Hopper estimates 15 per cent of the region's plants remain unnamed.

"That's a percentage that is equal to or exceeds most rainforest areas," he said.