How Australia's fragile native orchids could be evolving themselves towards extinction (2024)

Many Australian orchids have a peculiar charm but could this be the most charming of them all?

The charming spider orchid leads a certain type of wasp on a merry dance.

The bamboozled insect is seduced by the orchid's scent, enticed onto the flower's labellum, and unwittingly becomes the orchid's tool for propagation.

Happily, no wasps are harmed in this deception.

The spider orchid emits a pheromone that mimics that given off by a female thynnid wasp. This attracts male wasps to do the orchid's pollination work for it.

That's just one of the weird and wonderful ways Australia's native orchids have evolved.

Of the 400 native orchids found in Victoria, about 200 are considered rare, threatened, or endangered.

It is a similar tale across Australia in general. About half of Australia's 1,500 native orchids are at risk, according to Australasian Native Orchid Society conservation officer Garry French.

The charming spider orchid — Caladenia amoena — is one of Australia's rarest with perhaps only a few hundred in the wild.

It is listed as critically endangered both in Victoria and nationally.

If it weren't for the Australasian Native Orchid Society's efforts, it may have already disappeared forever.

"We've helped keep it alive," Mr French said.

"If we hadn't done what we did, this species would potentially be extinct. Potentially it would have been gone for good."

Evolving towards extinction

Orchids, as a family, are not especially uncommon. They represent the second-largest family of flowering plants on the planet, behind the daisy family.

All have evolved to be dependent on mycorrhizal fungi for their nutrients.

This highly evolved nature and symbiotic relationships with fungus and other organisms, such as insects, made many orchids vulnerable to habitat change, Mr French said.

"Some orchids in Australia have evolved to make themselves rarer than they should be," he explained.

"Being so highly evolved with so many specialist connections, maybe they have evolved towards extinction."

The charming spider orchid's range is limited to small clusters in central Victoria.

In the mid-1990s there was a single population in Plenty Gorge Park to the north of Melbourne and a population on private property at Wattle Glen.

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"I got involved in working with this species back then and we've worked to protect those populations, doing hand-pollination, and micro-site management of the areas where the orchids live," Mr French said.

"In 2003, I got approval to translocate from Wattle Glen to another site in Plenty Gorge where Caladenia amoena had previously been recorded but had been lost in that area. We did some direct seeding and got some really good results.

"We translocated 13 plants and got up to 43 plants in that population, which is really good for Australian orchids. Then the millennium drought hit, and a lot of orchid species started to regress and some started to die out."

Mr French said the drought led to a reduction of the population of Caladenia amoena from the private property site as well.

However, he said when rainfall returned and people felt things had returned to normal, the charming spider orchid continued to decline for a period.

Mr French said it took a few years until the population stabilised.

Conservation plan working a charm

Since 2017, the Australasian Native Orchid Society, Nillumbik Shire Council, and the Victorian Department of Energy, Environment and Climate Action have conducted a program to grow more charming spider orchids.

A batch of 400, grown by Royal Botanic Gardens Victoria in Cranbourne, has been planted into the wild at Wattle Glen and at two new sites.

Members of Australasian Native Orchid Society (Victorian Branch) are optimistic about the charming spider orchid but others are also threatened by the relentless sprawl of Australia's larger cities.

The society is actively engaged in conservation work with the small golden moths orchid — Diuris basaltica and the sunshine diuris — Diuris fragrantissima.

"The biggest threat is the degradation of habitat," Mr French said.

"If the habitat is healthy and functioning, the mycorrhizal fungi will be happy and active and the wasps will be happy and doing their thing and pollinating the orchid.

"The habitat has declined over time because of development on their borders."

Mr French said in the early days, sunshine diuris orchard — Diuris fragrantissima — was growing in several sites in the west of Melbourne.

But as Melbourne settled, the orchid became more restricted to one known site within Sunshine along rail land.

All other sites have been built up.

"Development has also impacted Diuris basaltica, which also likes the volcanic plains areas and that has impacted, first by grazing by cattle, followed by industry and housing," Mr French said.

"A lot of those habitats have been lost now.

"There is also an issue with orchid conservation with people wandering through and trampling areas to see these rare orchids or orchids in general. That is part of the problem."

Tread lightly, please

Native orchids can be appreciated in their natural environment without causing harm. There are rules to follow, though.

Colac-based textile artist Irene Pagram, who uses wildflowers including orchids in her imagery, says it should go without saying that picking the delicate flowers is not on and treading lightly is also important.

"I was raised to look [not touch] and everyone now effectively has a camera in their pocket," she said.

"If you are just starting out, look for something on the map that's actually named a wildflower walk. That way you will find the flowers without trampling through the bush."

Ms Pagram said it required quite a "slow way of walking".

"You should also know what you are putting your foot on with each step, whether it's on an orchid or a tiger snake," she said.

"Get your 'orchid eye' in because they can be smaller than your thumbnail."

But once the orchid photo is taken, Ms Pagram recommends discretion.

"We may share photos on social media but we don't tell where we have found them," she said.

"You can put the postcode but that's it."

Dazzling diversity

Australia's 1,500 native orchid species come in an extraordinary variety of shapes, sizes, and colours.

Neil Anderton from Australasian Native Orchid Society (Victorian Branch) describes 10 you may be lucky enough to spy.

Charming spider orchid (Caladenia amoena): extremely rare, blooming in just a few locations in late winter.

Flying duck orchid (Caleana major): found across Victoria apart from the far north-west, and flowers in late spring.

Fringed helmet orchid (Corybas fimbriatus): grows in South Australia and south-western Victoria. An autumn bloomer.

Flat rustyhood orchid (Pterostylis planulata): flowers in late spring across a very limited range around the Grampians in Victoria.

Purple hyacinth orchid (Dipodium punctatum): found throughout central and eastern Victoria in dry forest and woodlands. Blooms in summer.

Leopard orchid (Diuris pardina): very widespread across eastern Australia, including Tasmania. The 25-millimetre-sized flowers appear in late winter.

Nodding greenhood orchid (Pterostylis planulata): common across south-east Australia. Blooms in winter and spring.

Emerald-lip greenhood orchid (Pterostylis smaragdyna): found in damp, shady forests in central Victoria. Similar to green-striped greenhood (Pterostylis chlorogramma) in southern Victoria. Flowers appear in late winter.

Salmon sun orchid (Thelymitra rubra): found in a band from Adelaide to Albury. Blooms in spring.

Wine-lipped spider-orchid (Caladenia oenochila): scattered through central and western Victoria, especially the Grampians, and flowers in late winter.