Pauline Myer’s Caladenia falcata and Caladenia carinsiana;
Margaret Lee’s Diuris orientis and Nemacianthus caudatus;
Judy Sara’s Arachnorchis tensa;
Greg Sara’s Arachnorchis stricta which had an unusual green coloured flower;
and Helen Lawrence’s Arachnorchis argocalla.
Helen’s picture of the nationally endangered A. argocalla was the outstanding winner. Now known as the White Beauty Spider Orchid^, it was featured last year as a winner with Pauline Meyer’s June 2015 entry*.
This is one of our largest spider orchids. For size, beauty and delicacy it rivals the Western Australian Caladenia longicauda ssp. eminens (White Stark Spider Orchid) and A. venusta, syn. Caladenia venusta (Graceful Spider Orchid) from Victoria and the South East.
It shares many similarities with these two species in that they are reasonably good size white flowers with a stiffly hinged labellum that has long, thin teeth and the segments have threadlike tips without clubs. It is separated both geographically and in the type of habitat from these two species. A. argocalla is a plant of the inland hills and valleys.
Though primarily a white flower and part of the A. patersonii complex, A. argocalla has red colouring in the labellum which according to Backhouse may possibly indicate genetic introgression (that is long term mixing of the gene pool) with either the A. reticulata or A. leptochila complexes. Certainly, the colour of the labellum was quite variable ranging from white through to a deep red.
^Previously known as Common White Spider Orchid because of its abundance but now only known to a limited number of locations.
*NOSSA Journal, July 2015
Department of the Environment (2016). Caladenia argocalla in Species Profile and Threats Database, Department of the Environment, Canberra. Available from: http://www.environment.gov.au/sprat. Accessed Thu, 3 Nov 2016 16:31:39 +1100
This week’s blog, Part One of Two Parts, is quoted directly from the introductory chapter (Pages 2&3) Orchid Pollinators of Victoria 4th Edition, 2016, Rudie Kuiter. Over the years of photographing orchids and their pollinators, Rudie and his team have been discovering much of the hidden world of orchid pollinators. In this first section he highlights the fallacy of the “one orchid-one pollinator” as well as touching briefly on the vast difference between the insects and their role in the ecosystem.
Amongst flowering plants, orchids have evolved in their own special reproductive ways. Their pollen is massed as waxy packages, pollinia, unlike like (sic) other flowers that produce masses of fine pollen grains that mostly go astray. The pollinia are relatively heavy and the usually small creatures need to be strong fliers for cross pollination (see image below). Orchids evolved with amazing strategies to attract specific carriers in order to transfer pollen between flowers of their species only, and in this way eliminating the need to produce great quantities. Various insects, many moths, bees and even birds have been documented as pollinators of orchids around the world (v.d. Cingel, 2001). A number of uniquely different examples of orchids attracting insects for their pollination evolved in Australia, especially in the more temperate southern zones originating from Gondwana times. With very few exceptions the Victorian orchids are terrestrial, ground-dwellers, that rely on small insects such as fungus-gnats, native bees, wasps, ants and many attract only the males by sexual deception. In the case no pollinators visits, many species may self-pollinate as a back up.
When taking an interest in orchids it seems difficult enough to identify some species. Usually one looks and admires the amazing flowers that may resemble an insect and can be difficult to recognise as a flower at first. An insect on a flower may be thought of something that spoils a picture – until taking an interest in the visitor!
I first learned about the orchid pollinators in Orchids of South Australia by Bates & Weber, 1990, an excellent book by today’s standard, but few were seen over the years by just being there at the right time when photographing orchids. During preparation of the book on Caladenia spider-orchids, certain issues developed from questionable statements made in scientific papers about wasp-pollinators. Of particular concern was about the one-to-one relationship – how only one wasp-species would be involved with only one spider-orchid species – and suggesting populations that were thought to represent the same species comprised different taxa if not pollinated by the same wasp-species. A very different story emerged when monitoring the local spider-orchid populations to find the answers and it became clear that there was much more to it. A site in Wonthaggi with a very large colony of Caladenia dilatata proved to be perfect for this study and also to photograph pollinators as it produces flowers for about four months. It was found that a local wasp-pollinator species typically flies for a little over one month, thus this need to be investigated further. Scientific publications on wasp-pollinators were generally based on short-term experiments, and usually employing baiting methods – moving flowers and often taking them to different sites. Responses included unnatural behaviour or attracting sibling wasps at a non-local site. It is certainly true that a particular flower may attract only one species of wasp a t a locality and a certain time in the season, but this reflects a very small part of the picture. It can be different in the long-term, at certain localities or with a season.
The main study site was in coastal dunes, where in a very large population of Caladenia dilatata produced flowers for over four months from September, and under favourable Summer-conditions into January. At least three congeneric (belonging to the same genus) thynniid wasps species were involved in this population. The flying times were up to about 6 weeks for each wasp species, that were separated or slightly overlapping. The flowering times in other populations of C. dilatata in Wonthaggi and Wilsons Promontory were usually about one month in each, and at the corresponding times to the study site the wasps visiting were the same species. A close sibling C. parva in the Wonthaggi heathland habitats and early flowering C. dilatata were pollinated by the same species, but the later flowering C. tentaculata by a thynniid wasp of the different genus.
Whilst a flower may attract only one wasp species, the kairomones (chemical omitted by the orchid to attract a pollinator) of a species may vary between flowers within in a population or when allopatric (growing in different geographical regions), just like colour or morphology. Variations maybe in relation to locality, weather conditions, or ground chemistry and available pollinator. Pollinators may evolve over time, but adaptions usually require many seasons and this would vary with location. The observations made over several seasons suggest that more than one congeneric insect is involved in pollination depending on local or seasonal conditions, especially after a long drought. Chiloglottis gunnii populations in Langwarrin were checked for pollinators since a decade-long drought and no action was seen for many seasons. When wasps finally made an appearance they comprised different taxa of Neozeleboria the first season, but only one became the common and principal pollinator the following seasons. Thynniid wasps are very localised as females lack wings and rely on the males to carry them around during copulation and to provide food. It limits their travelling and their homing range may comprise just a few hundred metres. Thynniid wasp are very vulnerable in small reserves isolated by land-clearing, and certain species have gone locally extinct due to conducting burns. Insects form a crucial and fundamental part of an ecosystem, but their importance is never considered in the planned burning, showing a complete lack of understanding by people in charge. So little is known of ecosystem’s foundations, but controlled burning continues – ruining precious habitats. Orchid species failing to produce seed pods is an indication that pollinators were absent, probably gone locally extinct. Orchid species that have a sexual association with thynniid wasp pollinators are localised and usually have geographically variable flowers. The situation is different with Cryptostylis spp. And their pollinating male wasp Lissopimpla excelsa, as females are a strong flyers. The flowers of Cryptostylis are geographically uniform in each species and the wasp is widespread. Both sexes are very distinctive in colour that show no variation. They are active over Spring and Summer and are great travellers.
This week’s post is taken from the IUCN SSC Orchid Specialist Group Facebook post concerning Resolution decided upon at the final session of the International Orchid Conservation Congress Conference, held in May 2016 at the Kadoorie Farm & Botanic Garden, Hong Kong
It was posted by Michael Fay of Royal Botanic Gardens, Kew. He is also the Chair of the IUCN SSC Orchid Specialist Group. According to their website, “The Orchid Specialist Group is a global network of experts who volunteer their time and expertise to build a scientific and practical foundation for the conservation of orchids (Orchidaceae).”
(A list of the meanings of acronyms appears at the end of this post.)
Michael’s post follows
Here are the Resolutions from the final session of IOCC VI in Hong Kong:
Orchids are a flagship plant group with a high profile in human culture. They are known from all vegetated continents on earth but their occurrence reflects patterns in the global distribution of biodiversity and their intricate ecological associations, particularly with pollinators and mycorrhizal fungi, reflect sensitive ecosystem processes. Accordingly, orchids are indicators of ecosystem and climate health. Many orchids and their associated biota have been exposed to a variety of threats as a direct consequence of human-driven global change, with almost half of the ca. 27,000 known species now potentially at risk of extinction. Delegates of the IOCC support all efforts to research and mitigate these threats and secure environments on which orchids depend, and are committed to achieving meaningful conservation by recommending that:
The creation of orchid enhanced habitats is a priority for ecological restoration.
Enhanced in situ orchid protection requires the creation of orchid reserves. These will benefit a wide array of other species and biological communities and can be financed through various public and private sources.
The international and domestic wild plant trade is widely recognised by governments and civil society as a major threat to the persistence of many orchid species, and that its curtailment requires concerted government action and enforcement.
The propagation and cultivation of threatened orchids by small and local orchid enterprises should be supported for the sustainable production of orchids used in horticulture, medicine and food.
Orchid cultivation should be licensed and audited by government or other government-approved body through a national (or international) accreditation scheme that specifies adequate safeguards to ensure best practice. Propagated orchids should be traceable and distinguishable from wild orchids so as to minimise the risk of laundering wild plants.
National, regional and international networks should be established and strengthened for promoting in situ and ex situ orchid conservation.
The next generation of orchid taxonomists, ecologists and conservationists is nurtured through improved training, education, publicity and awareness-raising programmes.
Members shall strengthen the work of OSG by:
Facilitating and conducting national and global Red Listing of orchids, and contributing to the Sampled Red List Index (SRLI);
Monitoring and reporting on the illegal trade in orchids to national enforcement agencies and to TRAFFIC;
Reviving Orchid Conservation International as a vehicle for web-based education and channelling funding to orchid conservation programmes, along the lines of Birdlife International;
Embracing social media and other web-based interactive tools as dynamic and effective means of stimulating communication, raising awareness and building networks;
Using citizen science as an effective means of motivating individuals and amateur groups to record orchid occurrence (e.g. OrchidMap, iNaturalist) and help scale-up the collection of verifiable data;
Establishing and maintaining a global database of orchid reintroductions (including both successes and failures) and ex situ orchid collections that can be accessed and updated by members and which is linked to the IUCN Reintroduction Specialist Group;
Creating new sub-groups focusing on trade and molecular identification, to reflect important cross-cutting themes and challenges.
Thanks to Stephan Gale and Phil Cribb for producing the final version of these.
IOCC VI refers to the International Orchid Conservation Congress Conference was held in May 2016 at the Kadoorie Farm & Botanic Garden, Hong Kong
IUCN: International Union for Conservation of Nature
OSG: Orchid Specialist Groups
SSC: Species Survival Commission
TRAFFIC: Trade Records Analysis of Flora and Fauna in Commerce
It is always good to see other members submitting images for the competition. This month Rob Soergel entered Urochilus sanguineus growing with Bunochilus viriosus and Ros Miller a Caladenia cairnsiana. Others were Rob and Jenny Pauley’s mass flowering of short Urochilus sanguineus, Pauline Meyers’ Arachnorchis cardiochila hybrid (possibly with A. strigosa) and Lorraine Badger’s Diuris corymbosa.
The winning picture taken by Ros Miller C. cairnsiana (Zebra Orchid) is one of Western Australia’s unique and interesting orchids. It was first collected by Baron Von Mueller (Victorian Government Botanist 1857–1873) from the Stirling Ranges and subsequently named in 1869 after the Rev Adam Cairns a Melbourne Presbyterian minister who promoted “various philanthropic studies”. In the 2000’s various synonyms were applied to the name, most notably Jonesiopsis cairnsiana (2003).
Many of the distinctive features of this species are readily seen in Ros’ picture – the non-clubbed, equidimensional short lateral sepals and petals which are hard pressed up against the ovary; the smooth, upswept labellum. What is not seen is the leaf which is erect large pale green with the bottom third usually irregularly blotched with red-purple.
Flowering from August to November, occasionally in clumps, these orchids are distributed over an extensive geographic area from Lancelin approximately 130 km north east of Perth, to Israelite Bay near Esperance some 775 km south east. They grow in a range of habitats from forests, woodlands, to mallee heathlands.
Interestingly for such a widespread and colourful flower, they are often missed being seen as they are ‘small and hard to see’.
Brown, A., et al,(2013) Field Guide to the Orchids of Western Australia. Perth, WA: Simon Neville Publications
This is the last of the three terrestrial fact sheets in Culture Notes that NOSSA has produced on growing terrestrial orchids. All three facts sheets can be downloaded – Click on the following for Fungi Dependent, Slow Multipliers and Fast Multipliers.
Some 3/4 of Southern Australian terrestrial orchids are fungus dependent throughout their life cycle. Orchids that are fungus dependent have very specific cultural requirements. The fungus must be grown in the pot with the orchid. Sometimes a third entity such as a shrub or tree is involved in the fungal relationship.
A minimum disturbance culture is used.
Limited numbers are available each year. Other fungus dependent species are rarely available. Those in cultivation have mostly come from rescue digs in the past. NOSSA has started a seed kit project to help overcome this vacuum.
GROWTH HABIT: Australian ground orchids follow an annual growth cycle comprising 6 – 8 months as growing plants under cool (5 – 20°C max, 0 – 14°C min) moist conditions and 4 – 6 months as dormant tubers in hot dry (18 – 42°C max, 12 – 30°C min) conditions. The new tuber is produced in winter – spring. Each tuber sends up a shoot to the surface in Autumn and leaves grow rapidly in late Autumn/early Winter as temperatures fall and the rains set in. Sometime in October/November the leaves go yellow and then brown and dry as the days get longer, hotter and drier in late Spring.
LIGHT/SHADE: In Adelaide they thrive in a shadehouse of 50% shadecloth. Some species prefer heavy shade, others full sunlight, but most will adapt to a wide range of light intensity.
If the leaves and stems are weak and limp or if the leaf rosettes are drawn up to the light then the shading is too dense and the amount of light should be increased. FDs are mostly spring flowering and like higher light intensities at flowering time. flowers may have pale colours if placed in heavy shade, even temporarily, when buds are just starting to open.
In very cold areas an unheated glasshouse may be required for frost protection although light frosts do not worry the majority of species.
AIR MOVEMENT/HUMIDITY: All species like good air movement and will not thrive in a stuffy humid atmosphere especially if temperatures are high.
POLLINATION/SEED COLLECTION: FDs seldom multiply so must be propagated from seed.
Flowers on the strongest plants of the same species growing in pots are cross pollenated by hand to set seed pods. The flowers collapse in a day of so and pods ripen in 4-8 weeks. Pods are collected as they change colour from green to brown, which happens quickly on a hot day in October/November. Tea bags can be tied over the pods to catch the dust like seed if frequent visits to site are not possible.
Pods are stored dry in paper envelopes indoors over summer. Seed can be sprinkled on mother pots or scattered on bush sites.
SEEDLING CARE: Seedlings can be raised by sowing seed around potted mother plants.
At Easter time, just before the rainy season begins, the dust-like seed is mixed with fine sand in a pepper shaker (minimizes seed loss) and sprinkled on top of the pots and watered in. Germination occurs in Autumn/Winter as that is when the fungi are most active. Tiny leaves appear from July to October. The seedlings form miniscule tubers on droppers about 1 – 2cm below the surface. Seedlings take up to five years to reach flowering and are best left undisturbed until larger.
WATERING: The soil should be kept moist at all times during active growth by watering gently if there is no rain. Hand watering is especially necessary in spring as soil in pots dries out more rapidly than in the garden. Watering must be done slowly so that the mat of needles on the surface of the pot is not disturbed. Slugs and snails love these plants and must be kept under control. Raising the pots off the ground on galvanised steel benching is very effective in controlling these pests.
After the leaves have turned yellow, let the pot dry out completely to dry up the old roots and tubers otherwise they may turn into a soggy mouldy mess and rot may destroy the adjacent new tubers.
REPOTTING: The plants are not repotted but left in the same pot year after year.
SUMMER CARE: Keep the pots shaded and allow the pots to dry out between light waterings until mid-February when they should be set out in their growing positions and watered a little more often. The tubers of some species will rot if kept wet during the dormant period, others will produce plants prematurely which are then attacked by pests such as thrip and red spider and fungal diseases in the warm weather.
A thin layer of new leaf litter is placed on top of the existing leaf litter each summer to feed the fungus. Chopped gum leaves or sheoak needles are suitable.
There were four entries this month with two from Western Australia Pauline Meyers’s Caladenia flava and Ros Miller’s Caladenia longicauda sbsp. eminens; one local Greg Sara’s Pheladenia deformis; and one from the Australian Capital Territory, Lorraine Badger’s Cyanicula caerulea. The winner was the Caladenia flava.
If I was to think of an orchid that represents Western Australia it would be hard to choose between the Queen of Sheba and this one.
With its long flowering season (July to December) it is Western Australia’s most common and widespread species; being found in the south west triangle of the state from Kalbarii to Israelite Bay; in habitat as variable as the coastal heathlands through to inland rocky outcrops; from forests to swamp margins. Being so prevalent, it is not surprising that it was amongst one of the first Western Australian orchids collected in September to October, 1791 by the ship-surgeon and naturalist, Archibald Menzies. It was subsequently named in 1810 by Scottish botanist Robert Brown.
C. flava is one of the five species belonging to the subgenus Elevatae. The other four being C. marginata, C. nana, C. reptans (all WA endemics) and C. latifolia which is widespread across southern Australia. All five species have the same characteristic feature of the calli joined together on a raised plate near the base of the labellum. C. flava is distinctively and predominately yellow whereas the others are pink or white.
C. flava has two pollinators, native bees which are lured deceitfully to the non-existent nectar and scarab beetles (Neophyllotocus sp.). As they share the same pollinators, C. flava often hybridizes with C. reptans and C. latifolia, producing very colourful offspring.
Observations have led orchidologists to divide C. flava into 3 subspecies. These differences are based upon floral morphology. but curiously they each have their own separate distribution.
Brown A, et al, 2013 Field Guide to the Orchids of Western Australia
Hopper, SD & Brown, AP 2001b Contributions to Western Australian Orchidology: 2, New taxa and circumscriptions in Caladenia (Spider, Fairy and Dragon Orchids of Western Australia), Nuytsia 14:27–314.
QUESTION: Are there more than one species called Hare Orchid? This one [Leporella fimbriata] looks different from Leptoceras…? Why are they in different genera?
Originally they were described the genus Caladenia but as the knowledge information increased other genera were created. Thus Leporellafimbriata was put into Eriochilus, as Eriochilusfimbriatus (1882), then Leptocerasfimbriata and finally into its own genus Leporella (A S George 1971). Caladeniamenziesii became Leptoceras menziesii.
This does not answer the why of the question which is about classification but Jones (2006) is helpful when he says:
“Plant classification systems rely on interpreting and measuring the features in one group of plants and comparing these with another group, either seeking difference or similarities. Studies in orchids are usually biased heavily towards features of floral morphology but recent studies have revealed the importance of vegetative features in the roots, stems and leaves. The most successful classification system is one that is balanced and based on a wide range of vegetative and floral features.” To add to this list is the molecular studies being done on orchids.
This means the authors advocating change need to clearly show why a name change and/or a new species is warranted.
For instance, Fitzgerald gives the following reason for not including Leporella fimbriata in the Caladenia genus
“Leaves much more frequently observed than flowers. It is with great reluctance I depart from the naming in ‘Flora Australiensis’ [author Bentham, 1863 – 1878], but I cannot concur with the inclusion of this with Caladenia, and have place it in Lindleys’ Leptoceras for the following reasons: Leaf or leaves not those of Caladenia. In Caladenia I have never seen more than one leaf, always thin and usually hairy; in this plant leaf thick, hard and shining, occasionally two. In Caladenia tubers are generally numerous, in L. fimbriata I have only observed one. The labellum, is without the characteristic glans and is not of the form obtaining in Caladenia, the stigma is very different in form being triangular and deep sunk, the upper parts overhanging, not oval and shallow; and the flowers have the peculiarity of drying and continuing in a state hardly to be distinguished from the fresh flowers long after the seed has been shed. It approaches C. menziesii only (so far as I can see) in having erect linear-clavate petals, in which C. menziesii is itself peculiar, L. firmbriata seems to come near to Eriochilus than to Caladenia but differs from it again” Quoted from Emily Pelloe Western Australian Orchids 1930
Concerning Leptoceras menziesii, Bates & Weber have made the following statement:
“True Caladenias have hairy scapes and hairy leaves. (C. menziesii now believed to belong to a separate genus is glabrous)”.
Even though they are not Caladenia, why not have them in the same genus for both have glabous (without hairs) leaves, more leaves than flowers, erect spathulate (spoon shaped) glandular petals, colony forming, similar distribution.
There are similarities. In fact, Bates (2011) calls them sister genera but despite the similarities there are enough differences to recognise them at genus level at present including “different flowering times, different mycorrhizal fungi associations and different pollination” some of which are detailed in the chart below.
Winged male ants (Myrmecia urens)
Myrmecophyte – lives in mutualistic association with colony of ants
Curved white with red stripes
Wider than longer, purple and green
Has no calli
Spring (September to November)
Autumn (March to May)
Shaded sites – moist gullies; scrub, heath, woodland and foret
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).
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.
Think of deserts and the image is that of a bleak barren landscape with little to see but this is not so. The conditions are harsh but there is a myriad, though not an abundance, of hardy fauna and flora if one but looks closely.
But concerning orchids – No orchids have been found in true deserts….. They also appear to be absent from the arid mountains of the far north-west, or at least no-one has ever found orchids there.
Orchids need moisture and so they do not grow on unstable soils such as dry sand-hills, gibber plains or the many saline areas of the far north but on the desert fringes there are micro-climates where the moisture, humidity and soil structure is just right (to quote Goldilocks) for orchids. This micro-climate is created by [s]hrubland [which] is … [an] … important dryland orchid habitat. Besides providing shade and shelter for the orchids, shrubs like the many species of wattles, Acacia and hop-bush Dodonea drop fine leaves which help to hold the soil together and slowly break down into humus rich with nutrient and water storing capability. These shrublands usually form in soils too dry or shallow for trees. Orchids of course have no need for deep soils as they are shallow rooted.
Of the five desert botanical regions, the Eastern region contains the most number of species with over a dozen species.
Orchids of the Eastern Region – this region is from the east of the Flinders Ranges to the New South Wales border and includes the Olary Spur and Lake Frome.
Arachnorchis toxochila – Dry Land Spider Orchid or Bow Lip Spider Orchid.
Corunastylis tepperi – Mallee Midge Orchid
Diplodium robustum – Common green shell-orchid.
Hymenochilus pagophilus – Mountain Shell-orchid
Microtis eremaea – Desert onion orchid
Microtis frutetorum – Common woodland onion orchid.
Oligochaetochilus bisetus species complex, Rusty rufous-hoods
Oligochaetochilus sp. Blue-bush Plain – Blue Bush rufous-hood (O. bisetus complex)
The Gairdner-Torrens region includes, besides the salt lakes it is named after, the Gawler Ranges and the southern part of the Great Victoria Desert. Though not as many species as the Eastern region, it contains some different species including a Sun Orchid.
The final two regions Lake Eyre and North-Western contain the vast expanses of desert of the far north of South Australia. Definitely not a place to find orchids yet one specimen has been collected from each of these two regions.
Oligochaetochilus sp. Everard Range (L. Scott 173), Mimili Orchid (possibly O. woollsii complex) from North-Western Region.
Oligochaetochilus sp. Gammon Range (O excelusus complex) from the Lake Eyre region.
It is unusual to find orchids in the desert because they only grow when there have been good winter rains which isn’t very often. But nevertheless, here in South Australia we have over 20 possible species – an astonishingly high number for such a harsh area!
Bates R J ed, South Australia’s Native Orchids, 2011 Native Orchid Society of South Australia
Map adapted from Flora of South Australia, Fourth Edition, 1986
Recently, 10th February 2016, Anita Marquart, PhD student, Adelaide University spoke at the Field Naturalists Society of South Australia. She is a recipient of the Society’s Lirabenda Endowment Fund Research Grant. At the meeting she gave a summary of her research – Orchids, Insects and Fire: Investigating the impacts of prescribe burning on orchid pollinators in Southern Australia. Though she has not finished collating the data she has kindly supplied a summary of her talk with her preliminary findings.
It is always encouraging to see research on our native orchids. They are the Barometer of the Bush, so the more we can discover about them, hopefully the more we will better understand how to manage our native bushland.
Orchids, Insects and Fire: Investigating the impacts of prescribed burning on orchid pollinators in Southern Australia
Anita Marquart, Renate Faast, José M. Facelli, Andrew Austin
School of Earth and Environmental Sciences,
The University of Adelaide, Adelaide 5005 Australia
Fire is an important ecological factor in Australian ecosystems. Orchids that depend on specific pollinators may be more susceptible to disturbance than more generalist species. Therefore, declines or changes in pollinator communities due to prescribed burns and wild fires could lead to reduced pollination success and consequently declines in orchid populations. The project combines traditional plant and insect ecology with advanced molecular techniques to identify orchid pollinators and assess their response to prescribed burns and wild fires. Insect relevant habitat characteristics (such as floral abundance, vegetation height, presence of logs, litter and standing litter) were assessed and trapping surveys of potential orchid pollinators were conducted in spring, before and after prescribed burns. The effect of both spring burns and autumn burns is being investigated.
Study sites are located in the Adelaide hills with always one burn and one adjacent control site respectively in Kersbrook Native Forest, Millbrook Reservoir, Para Wirra Recreation Park and South Para Reservoir. Some parts of the study sites in Kersbrook and Millbrook were affected by the Sampson Flat Bushfire. Affected sites are used to compare the effects on orchid pollinators after prescribed burns in contrast to wild fires.
Potential orchid pollinators are being identified using DNA barcoding with the mitochondrial cytochrome oxidase I (COI) gene. Sequencing results will be compared with existing databanks and confirmed using morphological identification. As the data accumulates it will build up a reference library of COI barcodes for the species found in the surveys.
The outcome of this research project might help to advise the optimal management of orchid species under fire-managed regimes in the Mount Lofty region of South Australia, as well as more generally in south eastern Australia.
Orchids and their pollinators
Native bees, thyninne wasps and Syrphid flies are known orchid pollinators of South Australian orchid species. Orchids of main interest for this study were Caladenia rigida, Caladenia behrii, Caladenia tentaculata and Glossodia major. Caladenia tentaculata and C. behrii are sexually deceptive orchids and are known to be pollinated by thynnine wasps (Bates 2011). In contrast, C. rigida is food advertising and uses a broad range of bee and fly species, such as native bees and hoverflies (Faast et al. 2009). Glossodia major is a generalist in its pollination strategy and is using small native bees of several genera (Bates 2011, personal observations).
Syrphid flies were successfully separated into different species using DNA barcoding methods. Results show that we have two dominating species on our field sites in the Adelaide hills. Both species, Melangyna collatus and Symosyrphus grandicornis are common native Australian species. Both species were caught with orchid pollinia attached and were observed on Caladenia rigida flowers.
First findings suggest that hoverflies don’t seem to be much affected by prescribed burns or bushfires. Syrphid fly numbers vary greatly between the years of sampling, but we did not find a significant impact of prescribed burning or the Samson Flat bushfire.
Statistical analyses for the data on syrphids, native bees and thynnine wasps are currently underway.
Preliminary findings suggest that a range of pollinators are still present on field sites after prescribed burns and even after bushfires. Nevertheless, some specific species might be more sensitive to fires and might have disappeared from the study sites. For example, orchids relying on one species of wasp could be more affected by changes in the abundance of their pollinator after fire, than orchids that are pollinated by a number of different insects.
We will have to analyse our results in more detail to look into the specific species composition for the insect families, especially for native bees and thynnines, rather than looking at overall abundance.
Faast R, Farrington L, Facelli JM, Austin AD (2009). Bees and white spiders: unravelling the pollination syndrome of Caladenia rigida (Orchidaceae). Australian Journal of Botany57, 315–325.
Bates, R. J. (2011). South Australia’s Native Orchids. Native Orchid Society of South Australia.