Gnat-loving, fungi-eating orchid finds new home

News release
19 September 2019

Torrens Island orchid transplant team

Volunteers, ecologists and rangers have taken unusual steps to ensure that one of Adelaide’s rarest orchids doesn’t become extinct.

The Sandhill Greenhood orchid Pterostylis arenicola, a critically endangered species in the Adelaide and Mt Lofty Ranges (AMLR) region, has been transplanted to Torrens Island, once a quarantine site for infectious diseases.

The young orchids were germinated from seed collected from a tiny population of just a few hundred plants at Grange golf course, says Jerry Smith, Threatened Flora Ecologist with Natural Resources Adelaide and Mt Lofty Ranges.

“The Grange orchids are the only population in the entire AMLR region, with just two other known small populations from Tailem Bend and Wellington,” he said.

“With Friends of Torrens Island, we transplanted 32 young orchids into suitable habitat on Torrens Island. Early results have been encouraging, with the plants now flowering and looking like they will set seed,” he said.

“This exciting project will provide a significant back-up to the population at Grange - now we don’t have all our eggs in one basket!” Mr Smith said.

The Sandhill Greenhood’s green, red and white flowers produce pheromones which attract an insect called the fungus gnat. The gnat, confusing the flower with a potential partner, attempts to mate with it and in doing so, becomes loaded up with pollen. This pollen is transferred to the next flower as the fungus gnat continues its romantic adventures.

Mr Smith said the seeds are so tiny, propagating them is extremely challenging.

“They’re very fine - like dust - so don’t have the usual energy stores. Instead, the seed gets its energy for germination from a soil fungus.

“It’s only in the last five years that we have been able to successfully collect fungi from where the orchids grow in the wild, then isolate and grow the fungi in the lab and determine which one helps the seed germinate.”

Mr Smith said everyone can help protect Adelaide’s rare orchids by never disturbing or removing plants or flowers.

The orchid rescue operation is a collaboration between the South Australian Seed Conservation Centre, Natural Resources Adelaide and Mount Lofty Ranges, Friends of Torrens Island, the Native Orchid Society of South Australia, the respective land managers and the Threatened Plant Action Group.

This project is jointly funded through the Adelaide and Mount Lofty Ranges Natural Resources Management Board, and the Australian Government’s National Landcare Program.

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Natural Resources Adelaide and Mount Lofty Ranges