Orchids are unique in the floral world. Two distinctive characteristics that set orchids apart from other plants are the labellum and the column.
The labellum is a modified petal. It is extremely varied in appearance; “often lobed, spurred, adorned with glands, appendages of calli (callus, a hardened swelling or thickening of the skin), sometimes mobile and highly irritable and often brightly coloured”. * The labellum is important for pollination.
The column (as described by Bates and Weber) “is a distinctive feature of all orchids and a unique structure in the plant kingdom. It is formed by fusion of the male parts ‘stamens’ and female organ ‘pistil’.”*
Below are examples of the various types of labellums and columns in some South Australian terrestrial orchids. Each genus has its own characteristic labellum and column.
The following article by Les Nesbitt was published in May 2017 Native Orchid Society of South Australia Journal Volume 41 No 4. The article relates to Australian Native Orchids.
Suggested potting mixes for potted native terrestrial orchids have changed greatly over the years as some ingredients such as peat moss have become too expensive or difficult to obtain. Basic requirements are that the mix should be free draining yet retain moisture and should have an organic component that breaks down slowly and does not go mushy in winter. Most species are not too fussy and will grow in a variety of mixes.
Those tubers that desiccate in summer do better in a heavy mix that contains clay. Examples are Diurus behrii, D. punctata and Pterostylis nutans.
Tubers that rot easily in wet soil in Spring prefer an open coarse sandy mix. An example is Thelymitra antennifera.
A dry mix containing a higher proportion of sand is usually recommended for Caladenia and Glossodia species grown in pots. In contrast these orchids grow in clay soil on my property in the Adelaide Hills but there excess water can run off. In pots, excess water has to drain through the potting mix.
An organic component is vital to feed orchid fungi.
Some Basic Ingredients:
Washed sand with rounded particles. (Not sharp sand as this sets hard in summer.)
Soil (sandy loam, clay based loam, mountain soil)
Native seedling mix (Bark based – sieve to remove splinters)
Native potting mix (can be sieve* to remove larger particles)
Chopped and sieved* gum leaves
Perlite or isolite (but will make tubers harder to identify at repotting time)
Composted leaf mould & buzzer chips (but needs to be gathered now for use next summer)
Cauarina (She-oak) needles chopped for surface mulch
Some Suggested Potting Mixes
ANOS-Vic dry mix – 2 parts coarse sand, 1 part coastal sandy loam, 1 part composted buzzer chips, 1 part leaf mould
100% native potting mix. (Works for drought resistant tubers, viz. Pterostylis curta & P. pedunculata)
Native potting mix (sieved*) and isolite
Native potting mix and sand
Les Nesbitt’s current mix of 50% sand, 20% hills soil, 25% seedling potting mix (sieved), and 5% chopped & sieved* string bark gum leaves.
I have recently been learning about propagating orchid via flasks but I have mould in some of the flasks.
There is mould in the flask with orchid seeds and also in the flask with Diuris tricolour in bulbs. The bulbs are almost ready for deflasking.
What can I do?
With a home laboratory, no matter how careful one is, mould can still contaminate the jars of agar. If mould occurs when the orchids are still in seed, then the whole jar needs to be discarded. The seeds will not survive.
With the Diuris flask, as they are almost ready for deflasking, pot them out straight away. This needs to be done within 10 days of the mould appearing. The weather (March, 2017, South Australia) is still a little too warm but if left in the flask, the plants will die. Potting them out may give them a chance of survival.
When deflasking, it is important to rinse all the agar off the bulbs before potting on as normal. Once potted, it could help to cover the pot with a cut down clear drink bottle with the lid removed. This will allow some air to circulate. Keep the pot in a shady spot.
Will it survive in the pot? Hopefully it might but at least the plants have a better chance of survival then if left in the flask where it would surely die.
Orchid names are contentious. The reasons appear to be complex but whatever the reasons the situation exists whereby some orchidologists are naming species that may or may not be accepted by others. The result is that there are publications using different names for the same species. And of course, in the midst of it all, are those names that have been accepted for previous species with phrase names or manuscript names.
Whatever the name, it is helpful then to be able to match them up. Last week’s blog covered South Australian names but in the same week Andrew Brown published on the Western Australian Native Orchid Conservation Study Group Facebook an updated list of WA orchids whereby he has linked them with significant WA Orchid field guide books.
Andrew has kindly given permission for this list to be published. Other lists are also included and these are available on the NOSSA’s Orchid eBook page.
It is worth reading Andrew’s introduction in ALIGNMENT of WESTERN AUSTRALIAN DIURIS AND PTEROSTYLIS NAMES.
The object of this exercise is to align the phrase names in these three publications with names published in recent taxonomic papers. Please note that most, but not all, currently recognized (described and undescribed) Western Australian Diuris and Pterostylis are included. There are other taxa that may be considered worthy of recognition but have not been included at this time as we feel further research is required.
In the case of phrase names, these are added and removed for taxa as new information comes to hand and should not be thought of as the final view. Rather, these should be thought of as current thinking that may change in the future. Taxa are only formally recognized as being distinct once their scientific names are published. Even then, later thinking may result in further changes.
Given that phrase names are a work in progress, some may think that we should not be promoting their use and that they should not be included in popular books. However, I think it is worthwhile putting them out to the wider audience so that their distinctiveness can be debated. Having a large group of people looking for (and at) these taxa provides us with a great deal of information and opinion based on firsthand experience in the field, that we may not otherwise have obtained. Then, if and when the taxon is formally described, it will be done on a much more informed basis.
As I am sure you are aware, the naming plants is an evolving process and there will be further changes as new information comes to light.
The following video is by Orchid Hunter, Julian Pitcher. Julian is concerned about the conservation of orchids and is also keen to teach others about Australia’s unique orchids. At the time of the visit, Julian was resident in Victoria; now he resides in Queensland. Enjoy an interstate visitor’s view of our beautiful orchids.
The second fact sheet in Terrestrial Culture notes is about Slow Multiplying Terrestrials.
FLAGBEARER SPECIES: Thelymitra nuda
Diuris, Pterostylis and Thelymitra. They are more expensive because they have to be raised from seed in flasks. SMs are not so easy because there is less room for error. A few have a near zero increase rate and will fade away unless additional plants can be produced to make up for occasional losses from predators and disease.
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. Pterostylis leaves are usually the first to appear in March/April followed by Diuris and Thelymitra in April/May. 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:Australian terrestrial orchids are easy to grow. 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. Sun loving species (Diuris, Thelymitra & Rufa group Pterostylis) prefer a brighter location for good growth.
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. The spring flowering species like higher light intensities at flowering time and flowers may have pale colours if placed in heavy shade, even temporarily, when flowers 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.
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.
POLLINATION/SEEDCOLLECTING:Flowering plants are hand pollinated and the seed collected just before the pods split open and the dust-like seed blows away. The seed is sprinkled on pots of mother plants at Easter or flasked.
REPOTTING:Repot every second year in half new mix. Repotting is normally done between November and January. The best results are obtained if the tubers are repotted in half fresh soil mix each second year. A suitable soil mix is 40% loam, 50% sand and 10% organic matter with a little blood and bone fertiliser added. A 5 mm sieve is a useful tool for separating tubers from soil. Replant the dormant tubers with the tops 20 mm deep. Cover the soil surface with a mulch of sheoak needles, chopped to 20 – 50 mm lengths, to prevent soil erosion & aerate under the leaves.
INCREASING PLANT NUMBERS:The pull-off-the-tuber method can be used with some diuris and Pterostylis species to double plant numbers annually. The pots can be knocked out and the tubers examined in Summer without harm.
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.
FERTILIZING:SMs will benefit from weak applications of folia feed in the early growth stages.
Again this month was a varied selection of species with Pauline Myers’ Caladenia chapmanii (WA), Claire Chesson’s Thelymitra rubra, Jenny Pauley’s hybrid of Arachnorchis brumalis x conferta, David Hirst’s Caladenia discoidea and the winning entry, Rosalie Lawrence’s Diuris brevifolia.
This strikingly yellow flowered donkey orchid endemic to South Australia is listed as Endangered. Its range was once quite widespread in the southern Adelaide Mt Lofty Range region but now it is now restricted to pockets on the Fleurieu Peninsula and western Kangaroo Island in Heathy Woodland, Wetland and Riparian habitats.
There is interest today in cultivating orchids for conservation or ex situ conservation. With the reduced range of this species, can it be cultivated and thus continue to ensure its survival as a species? Some sources seem to suggest that it is an easy plant to cultivate, and some Diuris are easier than others, but Les Nesbitt points out that he has some plants from a rescue dig several years ago and that they have not multiplied very much in that time. This suggests that they may be dependent on a specific fungi. Though it has not been hugely successful in cultivation, it is worth noting that it has been used to produce hybrids with several other Diuris.
Bates, R. J. (2011) South Australia’s Native Orchids NOSSA DVD, Adelaide
Nesbitt, L personal communications
Adelaide and Mount Lofty Ranges South Australia Threatened Species Profile Fact Sheet – Diuris brevifolia
Western Australia produces a lovely array of orchids and so it is not surprising to find in NOSSA photograph competitions that when a Western Australian species is entered it can often be the winner. This month was no different with Pauline Myers beautiful picture of a mass of Diuris hazeliae which was kindly identified by Andrew Brown.
This species has only recently been named in 2013 and as a result finding information was a challenge. Obviously there was no information in Jones Native Orchids of Australia (2006); and surprisingly the definitive Field guide to the Orchids of Western Australia (2013) A Brown et al did not appear to have any information.
the Western Australian Herbarium’s FloraBase (Western Australian Flora), has a map of distribution which is roughly a diagonal line from east of Geraldton to the north of Esperance. It is not listed as threatened.
the Western Australian Herbarium lists the species as one of 59 new taxa added to their plant census in 2014.
from the Atlas of Living Australia it can be deduced that the flowering time is mainly August and September and is likely to be found in various types of shrublands margins including Eucalypt and mallee woodlands and appears to be mainly associated with rocky or granite outcrops.
and the National Species List APNI/APC yields the information that it was named after Hazel King, plant collector and conservationist with a special interest in orchids and was previously known by the phrase name Diuris ‘northern granite’ with a common name of Rosy-cheeked Donkey Orchid. It was found in a granite outcrop on her property Tampu (north of Beacon).
Fortunately Andrew Brown was able to help with extra information. It is listed in his book (page 212) but under the phrase name Diuris sp. Eastern Wheatbelt (Yellow Granite Donkey Orchid). Diuris sp. Northern Granite was found to be the same species and so the use of that name was discontinued but it does remain a synonym for Diuris hazeliae.
The following description is information updated from his book “Field Guide to the Orchids of Western Australia”
Diuris hazeliae D.L. Jones & C.J. French (yellow granite donkey orchid)
Flowering: August to September.
A common, inland donkey orchid 100 to 300 mm high with two to three basal leaves 50 to 150 mm long by 5 to 10 mm wide and up to seven predominantly yellow, brown marked flowers 20 to 40 mm across. Flowers are characterised by their broad petals, very broad dorsal sepal, narrow, reflexed, usually crossed lateral sepals and tri-lobed labellum with broad, spreading lateral lobes and a broad, flattened to convex mid lobe.
Found between Mullewa, Salmon Gums and Balladonia, growing in shallow soil pockets on granite outcrops and along drainage lines below rocky breakaways.
Named in 2013 from specimens collected at Tampu, north of Beacon in September 1997. The species often forms very large colonies on granite outcrops.
Inland granite and breakaway habitat.
Very broad dorsal sepal.
Diuris hazeliae is part of the Diuris corymbosa complex of which, in 2013, there were only 10 of the 26 Western Australian species formally named. This situation has now changed with 14 now formally named. As a final word, Diuris orientis is South Australia’s only member of this complex.
There is a lot of information on growing orchids so much so that it can become overwhelming. As a novice, I’ve put together my observations which can be summed up in three key points.
One – Find a Mentor
The best and first thing to do is to join a local orchid club, such as the Native Orchid Society of South Australia (NOSSA), and find a mentor within the group. There are many books but nothing substitutes for that personal interaction with an experienced grower who will know both the plant and the adaptions needed for the local conditions. At the monthly meetings, NOSSA has a Grower’s forum where various aspects of growing orchids are discussed and questions answered. It is well worth attending.
Two – Have an Equipment Kit
There are some things that are essential and it is good to have a basic kit to get started. Later, more equipment can be added as one’s skill develops in growing orchids. The necessary items would include:
Labels – these can be proper plant labels from a garden store or wooden lollipop sticks, so long as they are waterproof.
Pen – indelible ink pen or pencil (there are pencils that can write on plastic) as it is pointless having a labelled plant with the details washed off.
it may be necessary to use both current name and synonyms on the label eg Corybas/Corysanthes
Wettable Sulphur – necessary for guarding against diseases and is available from garden centres but Tomato Dust can be a good substitute although it is half the strength.
Good nursery hygiene techniques are important
Dilute bleach, tri-sodium phosphate (and possibly a small blow torch for metal tools)
a different sheet for each orchid when dividing will help prevent transference of any disease, etc (don’t forget handwashing)
Ties and Stakes
Sieve for recovering tubers
Sheoak or pine needles for putting on top of the pots to stop soil and fungi splashing up on the undersize of the leaves
Pots – do not need to be fancy but the pot size will depend upon the species
Diuris prefer deeper pots; Corysanthes prefer wider, shallower pots whilst Pterostylis doesn’t seem to mind either
Three – Work within the Plant’s Growing Condition
This will require time, research, experiment and going back to the experienced growers. Each one of us eventually needs to find what is the best setup for our individual location but some general guidelines would be:
Start with plants that are suitable for your current climatic conditions. Obviously putting a tropical Dendrobium bigibbum under the patio in temperate Adelaide is not going to be successful. For the terrestrials it is better to start with Pterostylis curta or a Microtis than a fungi dependent Arachnorchis tentaculata.
Research the plant you want to grow and then create the micro-climate necessary for the flourishing of the plant. This will entail separating the orchids, don’t put shade lovers such as Corysanthes with those requiring brighter light eg the Thelymitra genus.