PARK WATCH Article September 2026 |

Scientists at the Royal Botanic Gardens Victoria (RBGV) are saving threatened plants, report Dr Noushka Reiter & Dr Megan Hirst 

There are about 36,000 orchid species worldwide, with Australia home to almost 2,000. Sadly, 45 per cent of all orchids that have been assessed by the International Union for Conservation of Nature (IUCN) are threatened with extinction. In Australia, 216 of the 1,384 plants listed as threatened under federal nature law (EPBC Act) are orchids. Their effective conservation remains a significant challenge.

Victoria is in a unique position. All native plants assessed under state nature law (FFG Act) use IUCN regional threat categories to determine extinction risk at a state level. In Victoria, 1,622 plant species are listed as Extinct, Critically Endangered or Vulnerable. More than 200 of these threatened plants are orchids. Many of the plants, animals and fungi protected under state nature law only live in Victoria and would qualify to be listed under federal nature laws, which give a higher level of protection. Yet currently, many of them are not. As a result, many populations on private land lack protection. Tragically, orchids such as Caladenia brachyscapa and Caladenia thysanochila are already extinct.

Victorian orchids can come in a bewildering array of colours and forms, living in diverse habitats from the coast to the Alps. Orchids have evolved specialised relationships with pollinators and mycorrhizal fungi. Their pollination is particularly fascinating, exhibiting an extraordinary diversity of pollination strategies ranging from sexually deceptive orchids that attract male pollinators by mimicking female insect pheromones, to more traditional systems that reward pollinators with nectar. Many orchids rely on only one or a few pollinator species to set seed. Understanding these pollinator relationships and their distribution across the landscape is therefore critical for effective conservation.

Orchid seeds are the smallest of all flowering plants. Unlike many other plant families, orchids do not form a persistent seed bank in the soil, and are reliant on specific mycorrhizal fungi to germinate. In many cases, these fungi are undescribed by science. Once germinated, orchids face a myriad of threats, including herbivory by invasive species such as rabbits, deer, pigs, horses and goats, as well as impacts from overabundant native herbivores and invasive weeds. These pressures are compounded by climate change, historic and ongoing land clearing and habitat fragmentation, which have left many populations isolated, genetically depauperate and highly vulnerable to extinction.

For many Critically Endangered and Endangered plants, including orchids, addressing threats alone is no longer sufficient. Population sizes are now so small that active, species-specific intervention is required to prevent extinction and support recovery.

The RBGV Orchid Conservation Program aims to prevent extinction by:

  • Conserving genetically diverse collections of seed and mycorrhizal fungi.
  • Propagating permanent ex-situ conservation collections to support seed orcharding and reintroduction programs.
  • Reintroducing orchids to permanently protected public or private land where appropriate habitat, pollinators and mycorrhizal fungi occur.
  • Engaging landholders, local communities and citizen scientists in these activities to support long-term conservation outcomes.

To date, the program has established an ex-situ living collection of 212 species. The collection contains almost 30,000 plants grown symbiotically from seed with their associated mycorrhizal fungi. The orchid seed bank now holds more than 5,000 samples representing 30 genera and 310 orchid species from across Australia. In addition, the mycorrhizal fungi collection contains almost 3,000 cryopreserved fungal samples. Working with numerous project partners, the program has undertaken reintroductions at more than 40 sites. Despite these achievements, much work remains to be done.

Restoring Robust Spider-orchids to Raymond Island

The Robust Spider-orchid (Caladenia valida) was historically known from 17 populations across Raymond Island, as well as Anglesea, Portland and South Australia. More than 16 Victorian populations are now gone. On Raymond Island, Robust Spider-orchids have dwindled from 17 sites and over 575 plants in 1990, to three sites and less than 30 plants.

Emerging research suggests Victorian populations are a distinct evolutionary unit from those in South Australia. With the entire remnant Victorian population being fewer than 30 plants, urgent action was needed to bolster their genetic resilience. EPBC Act listing is warranted to secure them into the future.

On a chilly winter morning this July, a convoy of orchid enthusiasts, conservationists and volunteers descended on Raymond Island with a shared mission: to give one of Victoria’s rarest plants a fighting chance. Armed with measuring tapes, plant tags, stainless-steel cages and enough insect repellent to ward off an army of mosquitoes, the team set about returning hundreds of Robust Spider-orchids to the bush.

These orchids have suffered significant declines on Raymond Island, particularly following habitat destruction, flooding events and rising groundwater levels. To prevent extinction, RBGV has spent several years identifying and mapping their pollinator across the landscape. Research revealed that Robust Spider-orchids rely on a single undescribed thynnine wasp, belonging to the genus Phymatothynnus. Concurrently, conservation staff developed a genetically informed breeding program, propagated hundreds of orchids from seed collected on Raymond Island, growing them symbiotically with their essential mycorrhizal fungi in specialist conservation facilities at RBGV Cranbourne.

In Winter 2026, approximately 200 Robust Spider-orchids were returned to Raymond Island, providing critical reinforcement of the remaining population. Each plant selected for reintroduction was carefully assessed for size and vigour, measured and tagged before being planted within a protective cage inside a fenced conservation site. These measures were designed to maximise survival and support the establishment of a future self-sustaining population.

The scale of the project relied on an extraordinary community effort. Staff from RBGV worked alongside Gunaikurnai representatives, local landholders, the Australasian Native Orchid Society and the Bairnsdale Field Naturalists Club, Department of Energy, Environment and Climate Action (DEECA) and Trust For Nature to conserve these orchids. The planting day also included renowned orchid experts Gary Backhouse and Jeff Jeanes, Len and Josee Carrigan, and local botanist James Turner. Together, the team laid out planting grids, measured and labelled individual orchids, watered plants, installed protective cages and carefully planted each orchid into its new home. The reintroduction of Robust Spider-orchids was funded by DEECA’s Nature Fund. 

Looking into the future

Despite the depth of action for Robust Spider-orchids to date, RBGV’s work does not end here. The examination of flower morphology, pollinator specificity and genetic differences across the orchids’ currently recognised distribution will be used to better understand species boundaries and identify distinct populations that may require separate conservation management.

To improve the chances of the ongoing survival of Robust Spider-orchids, the possibility of additional translocation efforts is being assessed. This includes further reinforcement of known populations with novel genotypes and assisted colonisation into new locations in East Gippsland.

It is hoped that with these actions, the extinction risk for this little beauty will be reduced in the decades to come.

Dr Noushka Reiter (Principal Conservation Scientist) and Dr Megan Hirst (Seed Ecologist) worked on the orchid program with RBGV horticulturists Jade Bell and Chris Jenek

For further information about RBGV’s work, visit rbg.vic.gov.au/science

Tours of the orchid glasshouses run through to October. Go to rbg.vic.gov.au/cranbourne-gardens/whats-on-cranbourne/orchid-conservation-tours