In the plant kingdom, orchids stand alone. They're highly evolved, come in a countless colours, shapes and sizes, and have some very bizarre associations with insects.
Orchids are monocots (which means they only have one cotyledon – the leaf attached to the embryo within the seed).
Along with daisies they’re one of the largest groups of flowering plants. Their flower is bilaterally symmetrical and their leaves are simple, with parallel veins.
Orchids are pollinated by insects, though some species are known to self-pollinate.
Seeds are generally microscopic, and their germination depends on the orchids’ symbiotic association with underground mycorrhizal fungi.
We have 1,200 to 1,400 species of orchid in Australia, many are endemic (only found here). Australian orchids have remarkable specialisations, like the genus Rhizanthella , which spends its entire lifecycle underground; others are epiphytic, growing on trees or similar structures.
We have four species of rare orchids on our Victorian reserves, all of which are endemic to Victoria:
- the Northern Golden Moth (Diuris protena),
- the Robust Greenhood (Pterostylis valida),
- the Red-cross Spider-orchid (Caladenia cruciformis) and
- the Stuart Mill Spider-orchid (Caladenia cretacea).
Threats to orchids
These orchids have been pushed to the brink of extinction by a trio of threatening processes: land clearing for agricultural, urban and industrial development; grazing by stock and feral herbivores (especially rabbits); and weed invasion.
In the last 200 years their habitat has been greatly altered – grassy ecosystems are some of Australia’s most threatened.
Fire regimes have also changed dramatically in that time, and this has contributed to their catastrophic decline.
The Northern Golden Moth Orchid
The Northern Golden Moth is a deciduous, perennial, terrestrial orchid that emerges from an underground tuber. A bright golden yellow flower sits atop a 15cm green stem. This colourful species was first recorded in 2006, in the Terrick Terrick National Park. A large population of some 400 plants was subsequently discovered on our Nardoo Hills reserves in central Victoria in 2009.
The species is listed as Threatened (Endangered) under Victoria’s Flora and Fauna Guarantee Act. It’s suffered a catastrophic decline in range and abundance: almost all of the orchid’s habitat has been cleared for farming, or infested with weeds.
The Robust Greenhood Orchid
Nardoo Hills may be a small reserve, but it certainly holds some surprises. The Robust Greenhood was long presumed extinct until it was found on Nardoo Hills in the spring of 2009! Before then, the last sighting was in 1941!
The species has two to six translucent white and green striped flowers up to 2cm long on short, stout stalks. It flowers in October and November.
It’s listed as Critically Endangered under Commonwealth legislation, and Threatened (Endangered) in Victoria.
The Stuart Mill Spider-orchid
The Stuart Mill Spider-orchid is the third of our rare orchids found on Victorian reserves. This delicate flower is found on J.C. Griffin Nature Reserve, a 96ha reserve 185km north-west of Melbourne.
It has long petals – white with a reddish brown tip – and a 25cm stem. It flowers from late August to September and is very tricky to spot. The species is listed as Threatened (Endangered) in Victoria.
The Red-cross Spider-orchid
The Red-cross Spider-orchid also occurs on the J.C. Griffin Nature Reserve. More common than the Stuart Mill Spider-orchid, this species flowers in late September through to October. It has a spectacular crimson flower, with deep red clubs found at the end of each petal.
This species is usually found in small populations in areas of good quality, heathy woodland. It’s listed as Threatened (Endangered) under Victoria’s Flora and Fauna Guarantee Act 1988.
What’s Bush Heritage doing?
By looking after our Victorian reserves, Bush Heritage is safeguarding these precious orchids from extinction. We remove stock, manage feral herbivores and control weeds that smother and out-compete orchids.
On Nardoo Hills, for instance, our staff and fantastic volunteers control Patterson’s Curse, Horehound, Saffron Thistle and the Wheel Cactus. Our work allows these rare, delicate orchids to flourish.
What’s more, we’re actively involved in some very careful orchid reintroductions (plantings) to augment the naturally occurring populations. This program was funded by the Victorian Government and delivered by ecologist Julie Radford.
Plantings of the Stuart Mill Spider-orchid on JC Griffin Reserve occurred between 2014 and 2016. Over this three-year period a total of 142 individuals were reintroduced, with a survival rate above 70%.
Monitoring conducted over the past few years has shown that even in dry conditions this species is doing well, with an annual flowering rate of more than 50% within reintroduced sites and now self-seeding and natural recruitment taking place, increasing the local populations.
Also of note is a recent trial reintroduction of the Robust Greenhood into Nardoo Hills, with help from the Australasian Native Orchid Society, funded collaboratively through State and Federal programs.
Donate today to help us continue this and other vital conservation work.