This month’s competition consisted of two sections – the Flying Duck and the Little Ducks. The winner of the Flying Duck Orchid (Caleana major) picture was Patsy Love. Bob Bates provided a commentary on the Duck Orchids in South Australia.
Caleana major or Flying Duck orchid is unique and the unique shape of its flower was featured on an Australia Post stamp in 1986. It is found only in Australia and it ranges as far north as the Tropic of Capricorn, around the eastern seaboard, across to the South Australian/Victorian border where there is a gap until the southern section of the Mt Lofty Ranges. The latter distribution is know as disjunct because it is isolated from the main distribution group. In the Mt Lofty region, the range has been severely restricted. Records prior to 1983 show the distribution to be as far north as Cleland, Belair and Greenhill. Post 1983 distribution consists of a few isolated locations in the south. Though common in the eastern states, in South Australia it is listed as Vulnerable.
The factors contributing to the South Australian vulnerable status is the restricted distribution as a result of loss of habitat due to clearing, grazing, weed infestation, inappropriate timing of slashing, etc.
Another factor is lack of pollinator. Bob stated he has seen a male sawfly pollinating flowers (the labellum resembles a female sawfly) in New South Wales but no-one has ever seen it happening in South Australia. He also added that non-one has ever seen a naturally occurring seed-pod. It is suspected that the pollinators no longer live in South Australia. Thus it is important that the plants and their habitats are not disturbed.
The survival of the duck orchids is made even more precarious by their popularity. This seems to be the orchid that people most want to grow in cultivation. Sadly some people attempt to remove them from their native habitat. Tragically, when this does happen they inevitably die; no one, not even experienced growers, have been able to grow them in cultivation. It is important to concentrate on protecting its habitat if we are to continue to enjoy this unique species.
Calenana major, Adelaide Mount Lofty South Australia Threatened Species Profile, DEWNR, 2007