It’s Not Extinct at Ferris-McDonald After All

Leo Davis is an enthusiast about the natural world and shares his knowledge through different journals.  He is a keen observer and meticulous in his record keeping.  He is also very knowledgeable about orchids.  The following is one such article of Leo’s.

GOOD NEWS FROM FERRIES-McDONALD CONSERVATION PARK
Leo Davis

I was aware of the Star Spider Orchid from Bates who lists the species as ‘3E, critically endangered in South Australia, nationally rare’ (pp. 242–243). I knew that in the past it had been found at Monarto and Hartley and discussions with members of the Native Orchid Society of SA (NOSSA) suggested that it had been seen at Ferries-McDonald Conservation Park, but was now possibly extinct there. My searches over five years had all failed.
On August 2, 2014, I ran into, then strangers, Len Stephens and his grandson Rickey Egel, in Monarto C.P. They had just come from Ferries-McDonald C.P., about 8 km further south. Rickey, who has a very good eye for spotting orchids, showed me an image, in his camera, of ‘the common spider orchid’. From my hurried glimpse I knew immediately it was far from ‘common’ and told him so. I headed straight for Ferries-McDonald C.P. for the first of many fruitless searches.  On August 14, 2015 Rickey and Len showed me a few Star Spider Orchids in flower at Ferries-McDonald C.P. Because I was to lead the Botany Group of the FNSSA on an outing to Ferries-McDonald C.P. on September 5, I had been visiting the park almost weekly and so was able to spend many hours looking for the orchid. It is difficult to spot, being quite small. This year’s plants, perhaps not typical given the very dry June, are between 8 and 20 cm high with flowers only about 35 x 30 mm.
Plants were only found in Broombush (Melaleuca uncinata) associations. As soon as Eucalyptus species were present the orchid was no longer found.
Any survey, especially by a single person, will produce a lower count than the actual population. Leaves of non-flowering or beheaded (the fate of so many spider orchid flowers) plants will not be recognised, some flowers will not be spotted and some plants will flower before or after surveys, with some areas surveyed on different days. Between August 14 and September 5, 2015 just 18 flowering plants (Fig. 1) were positively identified (about the same number of likely leaves and buds, adjacent to these, were noted) over a narrow area of approximately 3,000 m2. The area searched was very much greater than this. Small as this tally is, it establishes a significant population other than the only other South Australian one that I know.  That is on the private property of farmer […], at Hartley. With his kind permission I have counted over 100 flowering plants there during five visits from July 28 (buds only) to August 30 (Fig. 2). The actual population will be larger because I did not cover all of that location. My observations suggest the populations I know to be around 150 to 200 plants with other occurrences probably existing around Monarto and Hartley.
Why have I avoided the scientific name? Many of you will follow the Electronic Flora of South Australia which lists the Star Spider Orchid as Caladenia stellata, as does Backhouse (pp. 456–457). I prefer to follow Jones (p. 76) (who does not recognise the species occurring in SA) and Bates (p. 242) (who says it does occur in SA), both of whom call it Arachnorchis stellata. Backhouse points out that the nearest other occurrence, the major one, is in central southern New South Wales, south of Rankin Springs, several hundred kilometres away, and that the plants there differ from our populations in having smaller flowers. He suggests that we are looking at a separate undescribed species, Caladenia sp. ‘Murray mallee’ (p. 484), but that it might indeed be co-specific with the Rock Star Orchid (sic), Caladenia saxatilis, which is similar and occurs further north, in the northern Mt Lofty and the southern Flinders Ranges. Bates told me in conversation, that he disagrees with Backhouse and believes the local plants are the same as those in NSW and distinct from A. saxatilis, which grows in soils of different pH (acidity).

 

Good News from Ferries-McDonald-1 38LD

Fig 1: Arachnorchis stellata, Ferries-McDonald CP,  August 22, 2015.  Photo: Leo Davis

Good News from Ferries-McDonald-2 38LD

Fig 2: Arachnorchis stellata Hartly, South Australia, August 5, 2015.  Photo: Leo Davis

BIBLIOGRAPHY:

Backhouse, G. (2011). Spider-orchids – the genus Caladenia and its relatives in Australia. DVD/pdf, Backhouse, Melbourne.
Bates, R.J. (2011). South Australia’s Native Orchids, DVD, NOSSA, Adelaide.
eFlora SA. Electronic Flora of South Australia; last updated August 22, 2015.
Jones, D.L. (2006). A complete guide to native orchids of Australia including the island territories. Reed New Holland, Sydney.

 

 

Used by permission, extract from The South Australian Naturalist Vol. 89 No 2 July-December 2015.

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