Native Orchid Rescue
| June 25, 2018
Australian native orchids have a complex relationship with their environment – they’re both an indicator of ecosystem health and a challenge to propagate. A program in central Victoria is successfully propagating and replanting the Stuart Mill Spider Orchid (Caladenia cretacea) in Bush Heritage Australia reserves in the area.
Some may call them fickle, but Julie Radford, an orchid expert from Amaryllis Environmental, sees native orchids as sentinels of an unseen world and reminders of a delicate web.
The thing that really captivates me about orchids is that they highlight those intricate relationships that happen in our environment that we don’t see with the naked eye or that we’re not aware of around us,” says Julie.
“And I think that’s why I’ve become an orchid conservationist; because they’ve helped highlight that nothing is isolated, and if you lose one element of an ecosystem, then gradually over time everything becomes lost.”
Julie has turned her attention to Bush Heritage’s John Colahan (J.C.) Griffin Reserve, a rare remnant of box-ironbark and grassy woodlands in north-central Victoria. There, she has helped to increase the number of threatened Stuart Mill Spider orchids from 12 plants in 2008 to around 186 last year.
The Stuart Mill Spider orchid (Caladenia cretacea) is a “very elegant, beautiful, dainty little orchid” that is endemic to Victoria and listed as threatened.
Like its bush orchid brethren, the Stuart Mill Spider orchid has a complex, interconnected relationship with its surrounding environment and is a good indicator of ecosystem health: healthy ecosystems beget healthy orchid populations.”
However, land clearing, grazing by stock and feral herbivores, and weeds have pushed the Stuart Mill Spider orchid close to extinction and continue to challenge the species.
“If you look at the box-ironbark country across central Victoria, we’ve actually only got about 13% of our native vegetation remaining. So the species that are trying to exist in these tiny little isolated, remnant patches of vegetation are really struggling,” says Julie.
To grow Stuart Mill Spider orchids, Julie needs to replicate a germination process that relies on a delicate dance between a particular pollinator, a symbiotic relationship with fungi, and the right environmental factors.
First, she needs to go out at flowering time and pretend she’s a bee. She hand-pollinates by taking pollen parts from one plant and inserting them into another.”
A few months later she collects the seed capsules containing thousands of tiny, microscopic seeds that look like finely ground pepper. She also takes plant tissue samples back to the laboratory at the Royal Botanic Gardens Victoria (RBGV) in Melbourne. There, RBGV research ecologist Dr Noushka Reiter, who leads the gardens’ orchid conservation program, can isolate the fungus responsible for germinating the seeds and grow it in petri dishes.
The seeds are then sprinkled onto the fungus, which inoculates them so they grow into tiny fluffy protocorms (tuber-shaped bodies). Eventually, after many more steps and three-to-five years, the plants are big enough to be transported back to the reserve for planting.
From 2014 to 2016, Julie did three plantings of Stuart Mill Spider-orchids at J.C. Griffin Reserve, with the help of volunteers from the Australasian Native Orchid Society, The St Arnaud Field Naturalist Club and the Kara Kara Conservation Management Network.
Their success is measured not only in the number of orchids that survived (60-80%) but also the flowering rates.
“Not all orchids will flower every year. Some might flower only one out of every three years, depending on weather conditions, but in 2016 I had a very good flowering rate of 50%,” says Julie.
For Jeroen van Veen, Bush Heritage’s Victorian Reserves Manager, the impact of the orchids on other species can be quite stark.
When we fence off a small area where we raise these orchids, we see the density of wattles increasing and the bush peas coming back in high numbers,” says Jeroen.
He says Bush Heritage is aiming for 1500 self-sustaining plants across the Stuart Mill district by 2030.
Bush Heritage acknowledges the support of The R E Ross Trust towards their efforts to conserve orchids in central Victoria, as well as RBGV staff, who are working to reintroduce 200 more Stuart Mill Spider-orchids back into their broader range by 2020.
Header image by Matthew Newton