Shane Grave’s winning photograph for April was the spring flowering Caladenia plicata which is endemic to the South West of Western Australia.
Caladenia is a very large genus with over 330 species, 39 of these currently unnamed. In addition, there are 58 named subspecies and varieties. Caladenia plicata would belong under the subgenus Calonema or the segregate genus Arachnorchis which, although not generally recognised by State herbaria is commonly accepted by many amateur enthusiasts. Yet even this subdivision is still large with 192 species. As a result, some authors have created further groups/complexes, for example C. dilatata complex, C.longicauda complex, etc. However, according to Andrew Brown, C. plicata doesn’t seem to fit neatly into any of these categories, although David Jones does include it within the clubbed spider orchids.
Various authors consistently refer to the labellum as being unusual. In Fitzgerald’s formal description (1882) he states that the labellum tip is “recurved so as to become plicate and touch the under surface of the disc”. Plicate means to fold. The labellum tip of many other Arachnorchis species are known to curl under but none fold under in the way that this species does. The sharp fold with the spreading horizontal fringed margins (edges) combined with a central band of tall dense calli (wart-like structures) gives a distinctive shape reminiscence of a crab, hence the common name Crab Lipped Spider Orchid. The effect of this is best seen from a front, rather than a side, view.
The very mobile labellum is sufficient to identify this species, but it is also possible to identify when in bud “due to the prominent short osmophores (clubs) on the sepals”. The sepals narrow halfway along to form thick brown clubs and when the flower is open both the lateral sepals and petals are downswept. This is clearly seen in Shane’s photograph.
The winning photograph for March 2019, was Corunasylis ciliata (syn Genoplesium ciliatum). As with so many orchids, it has undergone a few name changes. Originally Prasophyllum, then Genoplesium and currently Corunastylis
Although Genoplesium was split into two with only one species remaining in Genoplesium and the others placed into Corunastylis, this split has not been accepted by the everyone. For example, eflora of SA and PlantNET use Genoplesium whilst VicFlora uses Corunastylis.
Whilst researching C. ciliatum I came across images of Prasophyllum spp. being misidentified as Corunastylis spp. and as it was originally described in Prasophyllum it seems appropriate to examine the similarities and differences between the two genera.
In South Australia (SA), the most obvious difference would appear to be size but across the rest of the country some Prasophyllum species potentially can be similar in size to the much smaller Corunastylis, although Corunastylis species are never as large as many of the Prasophyllum species.
Some of the shared features of the two genera are
multi-flowered on a single stem
single tubular leaf
flowers non-resupinate, that is the labellum is above the column and the dorsal sepal is below (the only other non-resupinate flowered orchids in SA are Gastrodia, Caleana, including Paracaleana, and Cryptostylis subulata)
Grow as scattered individuals
Tends to be a larger plant (up to 150cm), but can sometimes be as small as Corunastylis
Always a small plant (maximum no more than 90mm)
Leaf sheaf opens well below the inflorescence (flower head)
Leaf sheaf opens at the base of the inflorescence.
Often withered at flowering
Not withered at flowering
Usually curved backwards (recurved) resulting in an upright appearance of the flower.
Not recurved resulting in a more drooping appearance of the flower
Mainly spring flowering
Mainly autumn flowering
Jones DL A Complete Guide to Native Orchids of Australia including the Island Territories 2006
Prasophyllum and Corunastylis descriptions from VicFlora, accessed 1 May 2029
Over the years, we have published several blogs concerning orchids and fire. At the beginning of the year, Renate Faast spoke at the NOSSA February meeting. John Eaton wrote an extensive summary of her talk which is reprodued here as it appeared in the 2019 March edition of the Native Orchid Society of South Australia Journal, Volume 43 Number 2.
Renate’s take home message was that we cannot make sweeping statement about orchids and fire, each species responds differently and we need to take this into account when planning proscribed. This was something that Dr Michael Duncan also brought out in his 2009 report following the Victorian Black Saturday fires – see Orchids and Fire.
An interesting aside to Renate’s research was her observations of white-winged choughs – see the paragraph Not All Relationships are Friendly.
Guest Speaker Notes John Eaton
At our February 26th meeting, thirty NOSSA members were treated to a stimulating talk by Dr Renate Faast from the University of Adelaide – our first guest speaker for 2019.
Renate acknowledged the support her project received from an Australian Research Council (ARC) grant under the Linkage Program which promotes national and international research partnerships between researchers and publicly funded research agencies – in Renate’s case – support from the University of Adelaide, SA Museum, SA Water, Forestry SA, The Australian Orchid Foundation, the Nature Foundation of SA, The Environment Institute and the SA Government.
Renate had been getting mixed messages from the field observations people had made following prescribed burning or bushfires. This ARC grant enabled her to study the impacts of prescribed burning on native terrestrial orchids.
Renate found that the response of orchids to controlled burns suggests that there are winners and losers amongst orchids: Naked sun orchids responded really well to a controlled burn with 6 plants growing to 83 plants. REALLY good news for that species of orchid but the reality is more complicated than that and this study suggests that there are no generalisations that can be drawn with any confidence about regeneration following prescribed burns or bushfires! In view of the complex interactions between orchids and other plants, and between orchids and bird-and-animal grazers, orchids rely on so many things to go right in order to set seed and recruit new plants into a population. With the exception of a few self-pollinating species, most orchids rely on pollinators for seed production. For non-clonal species, releasing seed is the only way to ensure the species’ long-term survival!
Not all relationships are friendly
Over 80% of orchid flowers had been grazed at some sites. No flowers means no seeds. Renate’s film clips embedded in her PowerPoint dramatically showed the extent of orchid predation by birds such as white-winged choughs and currawongs. They picked off the flowers quite deliberately, leaving behind an intact stalk. Five flowers were grazed every 10 sec (that’s at a rate of 30 flowers/min!) And there are all the other orchid grazers such as roos, deer and rabbits as they move through a patch, often only grazing part of the stem, in a far less targeted and thorough way, compared to these birds. All of these interactions play a key role in whether seeds are released to keep the population viable.
The Mount Bold Fire prompt
While engaged in her PhD research into reproductive ecology of spider orchids, Renate heard that a fire at Mt Bold had led to a “profusion” of Caladenia rigida flowers! The Victorian bushfires had also prompted changes to prescribed burning practises in South Australia. The combination of these two events led Renate to explore the effect of fire on the interactions orchids have with other plants and animals – leading her to ask such questions as:
Does fire promote the flowering of spider orchids (e.g. Caladenia rigida, C. behrii, C. tentaculata) and Glossodia major?
If there are more flowers following fire, will they be pollinated and will they set seed?
How does burn timing influence this response?
Do all species respond in the same way?
These are all critical issues to consider if we are to ensure a self-sustaining orchid population in the future.
There are seasonal influences on the effects of a burn. The response to a summer bushfire could be quite different from cooler season burns in autumn and spring. And even if some orchids are stimulated to flower, it doesn’t necessarily mean that they will end up producing and releasing more seed – which is what really matters for the long-term survival of the orchid population.
Orchid monitoring was carried out in several sites and included 1 autumn, 3 spring burns and 4 adjacent unburnt control sites across the Mt Lofty Ranges (NE of Adelaide). Renate followed the fate of 4 species by tagging up to 150 plants for each species. Renate’s presentation focused on the Millbrook sites where she studied C. rigida and G. major before and after a prescribed burn conducted in Autumn 2013. Unfortunately and fortuitously, her control site also became a bushfire site following the Sampson Flat Fire in January 2015. Fortunately, the Autumn burn site was not affected by the Sampson Flat Fire, so became something of a control site! Renate found that 97% of C. rigida did not emerge after the Autumn prescribed burn compared with 8% at the unburnt control affected site. Flowering was not promoted and no tagged plants flowered. A similar but less severe effect was recorded for Glossodia major.
Will these orchids recover in subsequent years?
Annual monitoring up until 2017, revealed that over one third of C. rigida plants did not re-emerge for 5 consecutive years after the autumn burn. Unfortunately, these plants are likely to have been killed by this burn, probably because the fire was conducted as the orchids were about to emerge. Interestingly, spring burns did not have a detrimental impact on the orchids studied, however, a proportion (18 – 28%) of C. rigida plants may also have been killed by the summer bushfires.
One of the more striking findings out of this research was the large increase in pollination for C. rigida following the bushfires – up to 65% of flowers (protected from grazing) produced a seed pod – an unprecedented rate for Renate’s research. It seems that in the sparse blackened landscape with very few other plants in flower, C. rigida had most of the attention for pollinators. However, the removal of understorey cover also meant that grazing rates were higher after the fires, and most of the flowers that were not protected inside cages were eaten. This meant that there was no actual benefit to the orchids, as there was no increase in seed release. All of these responses were short-lived, and by spring 2016, pollination, grazing and seed release rates were much the same as before the fires.
All species are not equal – fires may benefit some species others don’t fare so well; All fires are not equal; Autumn burning may be detrimental to SOME species; Bushfire may benefit seed release, only if grazing pressure is low – and Flowering was not promoted by any fire. More research is needed on other species, and in different habitats.
Therefore, Renate pointed out that no generalisations can be made about her observations!
Some good news that has come out of this research:
Burn practices are changing, with land managers taking into account the timing of prescribed burns, and bestattempts are made to avoid late autumn burns in areas containing threatened (early-emerging) orchids;
Impacts of fire on reproductive success appear to be short-term
Renate’s hope is that one day, the message will get out there that while some orchids can respond well to burning, this isn’t the case for all species – and that we still have a long way to go before we will really understand the complexities that underlie these different responses with any degree of predictability. Renate also warned that over a third of SA’s orchids are threatened with habitat loss, weed invasion, pollinator loss, grazing and fire regimes.
Renate’s address was followed by a flurry of burning questions and observations. It is hoped that we NOSSA members will use Renate’s conclusions to guide and inform our own anecdotal field observations and test our underlying assumptions and prejudices about the effects of burning on orchid viability – especially as we enter an unprecedented and potentially species-destroying period of human – induced global warming.
The following article by Les Nesbitt is taken from the Native Orchid Society of South Australia Journal, May 2019, Volume 43 No 4. The article has been slightly modified with editorial changes in black.
The majority of terrestrials will have leaves showing by month’s end. A few stragglers like South Australian Corybas and Western Australian Cyrtostylis huegelii will not appear until June so do not panic yet.
Pterostylis truncata (little dumpy) flowers this month with a large flower on a short stem. This species is given a blue tag to denote watering from January otherwise there will be no flowers under Adelaide conditions.
Tasks for May
Move the Autumn flowering greenhoods under cover as the flowers open because they generally have tall thin stems that will bend over under the weight of rain drops on the flowers.
Rot can be a serious problem in May. Do not overwater if there is little rain; and inspect plants closely and often. The rot can be on the leaves or below ground. Look for plants that are not thriving and give them a gentle tug to see if there are any
Move infected plants away from healthy plants to a hospital area under cover. Water from below by standing the pot in a saucer of water. Keep the leaves dry. Good air movement and at least 5 hours sunlight a day are essential for the next 3 months.
The fast multiplying orchids will appreciate a weak dose of liquid fertilizer once a month until spring.
Weeding is a chore this month as weed seeds germinate after rain. Pull them out while they are small maybe even with the help of tweezers.
Inspect plants closely for virus as the symptoms show in the emerging leaves. All plants can be infected with viruses of which there are many. There is no cure for virus. Infected plants must be destroyed to prevent virus spreading to healthy plants via sap sucking insects or human activities spreading sap. Infection during the growing season does not show up in the leaves until the following year. It is difficult to eliminate virus entirely hence the need to be vigilant.
Signs of Infection
Virused Pterostylis leaves may have light & dark green blotches or be thicker than normal and look crippled or turned up at the edges.
Another sign to look for are pointed pimples on Caladenia and Pterostylis
Virus is harder to spot on the narrow leaves of Diuris and Thelymitra. Healthy leaves are straight with almost parallel sides. Leaves that have kinks or are curved probably have a virus. Variegated blotching may be present in severe cases.
If only one or two plants, in a community-pot, show symptoms they can be lifted out soon after the leaves appear and before side stolons form.
A tool can be made from wire to do this. Bend a foot on the bottom of the wire and a loop handle on the other end.
Push the foot into the mix alongside the infected plant, rotate the foot under the tuber and lift the plant out.
At potting time (when tubers are dormant)
A sieve is a great time saver during repotting but at the same time an excellent way to spread virus.
Do not shake the sieve when tubers are present.
Pick out the tubers as you see them and drop them into a smaller kitchen sieve sitting in an ice-cream container of water. The sand and dirt wash off and falls through leaving clean tubers behind.
Use a jet of water to remove any remaining dirt.
Pat the lumps of mix in the big sieve to crush them to expose any tubers.
Shaking the sieve is the equivalent of sandpapering the tubers, a sure way to spread virus.
If several plants are virused it is better to dump the whole pot, soil and all.
Refuse new plants that look suspect.
ALL EFFORTS SHOULD BE MADE TO ELIMINATE VIRUS FROM AN ORCHID COLLECTION.
This article is a completion of the Thelymitra Column article which appeared in the NOSSA Journal, Volume 42 No 8 September 2018. Click here for Part One.
The first part looked at the features and terms used by botanists to describe various parts of the column, a major identification feature of the sun orchids.
And as previously stated we cannot physically dissect an individual flower, but we can make use of photographs to spot the various features.
The diagram below is that of T. nuda (based on the taxonomy of 1984) column whilst the photographs are that of T. glaucophylla column (as T. glaucophylla is one of the T. nuda complex). The column of these two are similar.
The following article by Les Nesbitt is taken from the Native Orchid Society of South Australia Journal, April 2019, Volume 43 No 3
Terrestrial Culture – April
The days and nights are cooling down, evaporation rates are dropping and pots take longer to dry out so decrease the watering. If in doubt wait another day before watering. Regular rain usually begins around Anzac Day. There is nothing like a good rain to make terrestrial leaves pop up almost overnight. A few early flowers are out this month – Eriochilus species and possibly Pterostylis truncata. Keep up the pest control and pull out weeds while they are still small.
Sow seed on pots around mother plants of fungus dependent orchids this month. Mix seed & fine sand together to avoid wasting precious seed. A pepper shaker helps spread the seed evenly. Water gently to wash the seed into the mulch.
April is a good month to deflask terrestrials. Seedlings need to establish & harden up before winter so get deflasking completed by the end of April. Check out flask suppliers for that special species. The next deflasking opportunity is early spring.
Deflasking Terrestrial orchids
Prepare a suitable soil mix for the orchid to be deflasked along with labels & sheoak topping. Use the same mix as for adult plants.
Select a flask with strongly growing seedlings, preferably with small tubers but plants without tubers are OK. Remove the flask lid and tip the mass of plants and agar into a fine sieve. If you are nervous remove clumps of plants from the flask with tongs. Try to minimize breakages. The junction of leaf & tuber is very weak. Over a sink or lawn, use a jet of water to wash away the agar leaving clean seedlings behind.
Fill a pot with mix to within 2 cm of the rim and tamp down. Select small clumps of seedlings and stand them around the edge of the pot. Insert a label with the appropriate info as this pot will not be repotted for 2 years. Pour a handful of mix into the centre of the pot and gently squeeze mix out around the seedlings just covering the bases but not burying the leaves. Add more mix if necessary. Tamp down the mix in the centre of the pot. Add a layer of chopped sheoak needles. Water gently to settle the mix around the seedlings.
The pot can go into the shadehouse with other terrestrial pots although it helps to keep all the seedling pots together in a sunny place with good air movement. Ensure the pot does not dry out. If kept too wet the seedlings may rot. If the seedlings establish and grow strongly they can remain in the shadehouse over winter. At any sign of rot move the pots out of the rain under cover and water by standing the pot in a saucer of water.
Next dormant season as soon as the leaves have died down, add more mix to completely fill the pot. This helps to protect the tiny seedling tubers from drying up in the heat of summer. After the second growing season the tubers should all be large enough to find easily at repotting time.
Welcome to our first competition for 2019. For February we had five entries which included Pauline Meyers’ Prasophyllum species from Western Australia, Lindy McCallum’s Glossodia major and Leptoceras menziesii, Lisa Incoll’s Thelymitra antennifera.
The winner was Rob Pauley’s photograph from the south east of Thelymitra malvina (Mauve Tufted Sun Orchid) which is found in only a few places in the South East but does occur in Victoria, New South Wales, Queensland, Tasmania and even ‘across the ditch’ in New Zealand where it is considered “an Australian species now established in the North Island”.
According to the Atlas of Living Australia, it is endangered in Victoria, South Australia, Tasmania; of Least Concern in Queensland and there is no listing for New South Wales.
This species has been included in both the T. nuda and T. pauciflora complex for, as Jeanes has observed, it has characteristics of both complexes such as the smaller flowering forms are self-pollinating, and the larger flowering forms are insect pollinated
Though the common name, Mauve Tufted Sun Orchid, indicates that its most distinctive feature are the purple tufts on the post anther lobe, it is possible to find them with white tufts and there are other species that have purple tufts (eg in SA T. azure and T. occidentalis may have purple tufts but it is obvious from their other features that they are not at all similar to T. malvina). There are no other closely similar species in South Australia, but on the other hand, in the eastern states, it can be confused with Thelymitra atronitida, so it is worthwhile considering some of the main differences between these two.
Although there are no other closely similar species in SA, in the eastern states it can be confused with Thelymitra atronitida, so it is worthwhile considering the differences
3 sterile bracts
2 sterile bracts
25 – 75 cms
30 – 50 cm
Slightly larger (but can have smaller flowers)
3 – 25 usually loose
2 – 8 ( – 16)
Reddish to dark brown with yellow apex
Glossy black with yellow apex
Post anther lobe
Moplike tuft of pink or mauve (rarely white) trichomes
Moplike tuft of white trichomes (hairs)
Across the country, there is some variations of flowering times with New South Wales having the longest flowering time from August to November and South Australia along with Tasmania having the shortest of October and November.
Bates RJ, 2011 South Australia’s Native Orchids, electronic
Backhouse G, Bush Gems, A Guide to the Wild Orchids of Victoria, Australia, 2016, electronic
As stated last month, this is the second in the series of terrestrial culture notes for growing orchids in Adelaide.
The growing season is underway although much of the activity is underground out of sight early in the month. Repotting should be completed by now. Repotting tubers with long shoots is a tricky business requiring very gentle handling. Broken shoots and the death of some plants can result. It is better to leave them until next summer.
The weather can be hot up until equinox on about March 21st. Be aware that autumn is a time of rapid change. Day-length decreases by 2 hours in the 6 weeks from the 1st of March. Our orchids respond to the longer cooler nights faster than we do. All pots should be in their growing positions for the coming winter. Increase watering in March so that by equinox the mix is damp right through to the bottom of the pot. The first Eriochiluscucullatus flowers are usually open by the last day of March with the majority blooming in April. The buds resemble a grain of wheat when they first emerge.
Thrip can be a major problem this month. Thrips love to suck on the flowers and will cause the flowers to shrivel up in a day or two. If using a pressure pack fly spray to kill thrips, hold the can at least half a metre away or you can freeze the flowers with the propellant. Repeat the spray every few days.
Pull out any weeds that germinate while they are still small. The early Greenhoods will be showing leaves and some of the blue tag Diplodiums may be showing buds. The Greenhoods will like a weak soluble fertiliser sprayed on their new leaves as they develop.
Deflasking can be done after equinox. April is the best month to deflask terrestrials as it is cooler and more humid with enough sun to harden the leaves before the cold and damp of winter. Flasks are often the only way to get the slow multiplying terrestrial orchids. Seedlings in flask that have tiny tubers establish more successfully.
Remove the second layer of shadecloth at the end of the month or first week in April. Keep up the night time hunts for pests which get more active as the nights cool.
Autumn is a good time to build or extend a terrestrial growing area. A terrestrial house should be sealed to keep out birds and animals and have shadecloth or wire mesh sides to allow the breeze to move through. I prefer a roof of angled 50% shadecloth. Other growers use a solid roof of plastic sheeting. A solid roof means you have to water your pots by hand, which is more work. It is very important that winter sun reaches your plants so site the shadehouse away from the winter shadows of buildings, high fences and evergreen trees. Galvanised mesh benching about 750 mm high will deter slugs and snails and is a convenient height for observing the pots.
With the lack of rains, it doesn’t look good for the start of the 2019 South Australian orchid season but there is a good news story.
In the February 13, 2019 edition of the Hills Valley Weekly there was an encouraging article of the work of Bush For Life. Part of Trees For Life, this program with the aid of trained volunteers spend numerous hours weeding specific bush sites with the hope that they give our native plants a chance to survive. Yes it requires commitment and dedication but what joy there is when volunteers start seeing plants returning.
Orchids are often the first to disappear from a site when weeds enter and in many instances do not return. For them to return the conditions have to be just right with both the mycorrhizal fungi and the pollinators present. The more orchid species the better the site.
So well done to Jenny McInernay and Trees For Life for their work and commitment.
The blue orchid featured in the article is a spring flowering sun orchid; it appears to be Thelymitra inflata, common names Blue Star Sun Orchid or Adelaide Hills Plum Orchid. The other flower is not an orchid. It is a Wurmbea, common name Early Nancy.