Journal Number 112
May 2009
AUSTRALIAN NOTES
By David McConachie
Exciting Discoveries of the Nationally Endangered Sun Orchid Thelymitra matthewsii Cheeseman in Two Separate Regions of
South Australia in 2007 and 2008.
By R Bates, K and B Bayley, C Houston and J Niejalke
Reprinted from The Orchadian 2009; 16 (3): 106-107, with the permission of the author.
Thelymitra matthewsii the Spiral-leaved Sun-orchid was first described in 1911 from
plants
collected in Mongonui County, New Zealand by amateur botanist R.H. Matthews.
The species was named in his honour.
The same species was redescribed in 1930 by Dr RS Rogers as Thelymitra daltonii from
Australian plants after being discovered by CW D'Alton in Victoria's Grampians in 1922.
Rogers later realised his mistake and reduced
T. daltonii to synonymy.
T. matthewsii was found in South Australia in the 1960s by Doreen Hunt in the Southeast
near Willalooka and Messent and on Kangaroo Island by Ida Jackson and by Rob Bates near
Kuitpo in
the Adelaide Hills in the 1970s and again by Bates on Kangaroo Island in 1992
when a single
plant was found in Flinders Chase after a bushfire.
By 1995 all South Australian populations seemed to have disappeared. The species had
occasionally been reported from Western Australia but Jones (2006) and Backhouse and
Jeanes (2006) reject it from that State.
By 2005 T. matthewsii had been declared as a threatened species for Australia as it was
known
only from small populations at a handful of sites in southern Victoria and the
Grampians.
It was considered even rarer in New Zealand.
Some thought it to be possibly extinct in South Australia. The Kuitpo population had been
ploughed up and planted to pines and despite thousands of man hours spent searching
by enthusiasts no plants were found at previously known sites. Climate drying convinced
many that it would never be seen again. Jones (2006) gave us some hope by reminding
that the species flowered best after bushfire's or disturbance and could not be expected
to flower every year.
Then in 2007 there came a breakthrough!
As reported by Andy Young in the October 2007 edition of the Journal of the Native Orchid
Society of South Australia, a colony of spiral-leaved Sun-orchids was found on Kangaroo
Island by the Island's resident botanist Bev Overton and Trish Mooney from the Department
of Heritage and Environment.
The actual location has been withheld but it is in a conservation reserve on the north-west
coast not far from the original discovery by Ida Jackson.
Young noted that he and others searched the area and found 22 plants growing along a
cleared path on lateritic soil and that a bushfire nearby had allowed ash to wash into the site.
Hence it could be observed that both the requirements suggested by Jones had occurred.
Only 2 flowers were found but the whole picture was about to change!
The 2008 breakthrough!
A planned orchid survey by NOSSA members of more than 90,000 hectares burnt on Kangaroo
Island in late 2007 did not take place due to lack of funding but luckily Forestry SA, based at
Mount Gambier in the State's Southeast region offered NOSSA funding to carry out an orchid
survey in one of its forestry reserves over three months from August to October 2008.
With a dozen members walking firebreaks recording orchid species in August amateur
orchidologist June Niejalke (with Dianne Richman) found several spiral sun orchid leaves
with
single buds and called us all over. The "experts" confirmed that her find was Thelymitra
matthewsii and by the end of the day over a hundred plants had been counted. Troy Horn
of Forestry SA advised that maximum protection would be afforded the population.
Flowers opened in late August and during the September leg of the Survey over a hundred
more were located on several tracks. All plants seen were on slashed heathy woodland in
leached sandy or sandy-clay soils.
Flowering continued for more than four weeks. Plants were single or had formed small clumps
of 2-4 plants.
No plants had more than one flower.
Flowers opened in temperatures as low as 15 degrees Celsius but were more prolific in
sunshine
and at higher temperatures. All flowers were self pollinated as pollinia collapsed
onto the stigma
even if blooms stayed closed.
No hybrids were observed and the only other sun orchid species in the area to flower by the
end of September was the yellow T. antennifera and these were several hundred metres away.
It was tempting to transfer pollinia by hand to see if the resulting crosses might produce
T mackibbinii but this was not done.
(T. mackibbinii was once listed from South Australia but the collections labelled as such in
Melbourne proved to be something else and T mackibbinii has been deleted as a South
Australian taxon.).
Management of the populations will continue as at present with slashing of the firebreaks
done after seed release in November. Ploughing will not be allowed but some additional
slashing and mosaic burns may be carried out in adjacent native vegetation.
Horses have occasionally trampled the plants and their hoof prints were still evident at the
time of our survey but signs will advise of horse riding restrictions in future.
The area is largely weed free except where ploughing occurs in damp areas.
Summary
This new population, estimated at 500 plants represents the first record of T. matthewsii
in the lower South-east district and appears to be the largest population in existence.
Dr Mike Duncan who has written recovery plans for the species notes that until this new
population only about 850 plants were known in the World. Its discovery gives hope to
the future of rare flora in South Australia as although annual rainfall has declined by as
much as 20% since the 1950s (which is only slightly less than most forecasts of long
term rainfall decline) species such as T. matthewsii are still holding on.
Curiously a single plant was seen in pod in the burned out Ravine de Casoars Wilderness
on Kangaroo Island in October indicating that there may be populations there too.
The actual localities have been withheld for security reasons.
References
Clements MA 1989. Catalogue of Australian Orchidaceae. Australian Orchid Research Volume 1.
Jeanes J and Backhouse G. 2006. Wild orchids of Victoria, Aquatic Photographics, Victoria.
Jones DL 2006. A complete guide to native orchids of Australia, Reed Australia.
Young A 2007. Thelymitra matthewsii rediscovery on Kangaroo Island, J. Native Orchid Soc. S. Australia,
vol 31. page 76.
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