Australia is a rich resource for orchids, especially terrestrial orchids which make up 82 percent of all the Australian orchids. Terrestrial Orchids are found, mainly below the tropics in grasslands, heath lands, and eucalyptus forests. Many are deciduous coming up in autumn/winter, flowering in winter/spring and dying down in summer. Most rely on fungi to survive, and for germinated to occur.
What makes an orchid?
Orchids are always made up of five main segments: a labellum, column, two sepals and a dorsal sepal and two petals.
How do orchids reproduce?
Most orchids need to be pollinated by native bees, wasps and sometimes ants. The introduced European Bee, because of its size, does not pollinate the flower, but can instead damage or destroy it. Some orchids do not require a pollinator and are thus called self pollinating.
Orchids in South Australia
There are many different orchids; in fact, South Australia is home to over three hundred different species, some of which are yet to be described. The Mount Lofty Botanic Gardens yields a variety of orchids, which will be covered in this leaflet.
Arachnorchis tentaculata King Spider Orchid
This species is relatively common in the Mt. Lofty Ranges, with flowers reaching ten centimetres across. It can easily be distinguished by clubs on the end of its petals and sepals.
Diuris pardina Spotted Donkey Orchid
This attractive flower is distinguished by the spots on its sepals and labellum. It received its common name as its petals reminded the English settlers of donkey ears.
Diuris orientis Wallflower Donkey Orchid
This distinctive orchid can be distinguished by its bright colours and particularly its labellum, which can be a shade of deep purple. This species is also referred to as the Bulldog Orchid.
Diuris orientis x pardina Pioneer Donkey Orchid
It is not unusual to find hybrids of the donkey orchid. It is often between these two species and can sometimes be difficult to distinguish from Diuris pardina.
Glossodia major Cockatoo Orchid
This purple flower is often found in fields, and is very common in the Mount Lofty Ranges. It does vary in colour from purple to a pure white, with the different varieties growing together.
Pterostylis pedunculata Greenhood
This winter flowering orchid is often found in dense colonies which can number over a hundred plants. It can be found in early spring in the Mt. Lofty Botanic Gardens.
Microtis arenaria Onion Orchid
This green flower breaks out of its cylindrical leaf. Many people find the Microtis family difficult to identify due to its minute size.
Thelymitra rubra Sun Orchid
This pink sun orchid is one of three pink sun orchids. It can be distinguished by the tufts on the top of the column. It opens freely on warm days, when the temperature is over 25 degrees centigrade.
Thelymitra brevifolia Pepper Top Sun Orchid
This sun orchid has a distinctive red top on its column. It can also be distinguished by red edges on its short broad leaf. Its flower is smaller than Thelymitra rubra.
Thelymitra parviflora Sun Orchid
This common sun orchid has a blue flower and can be confused with a number of other blue sun orchids. Like all sun orchids, it only opens on warm days, as this is when the pollinators are present.
There are many other types of orchids not considered in this leaflet. However some field guides on orchids will enable identification of orchids which can be found in other parks and reserves around Adelaide or beyond.
It is always a pleasure to find orchids but they do need to be protected and conserved. Orchids can easily be eliminated by weeds which choke them. Consequently, if orchids are found, it is an indication that the surrounding bush is good quality. It is also important not to pick orchids. Not only is it illegal, but orchids need their flowers to reproduce.
This is from a leaflet about the common orchids in the Mount Lofty Botanic Gardens. For the printable version, see here.