Protected: Photograph Competition September 2020
Monthly Terrestrial Orchid Culture – June
It’s June and the the orchids tubers are on the move. And yes there are some tasks for this month but as can be seen by Les Nesbitt’s notes in the June 2019 NOSSA Journal (Volume 43 N0 5) there is not a lot to do.
June is cold, often with frosty mornings and sunny days. Terrestrials can take -20C but any colder results in permanent damage. If you live in the country, you may need a solid roof for frost protection. Frosts are rare these days in Adelaide. I have black rubbish bins full of water under the benching in my glasshouse to moderate the temperature. The bins absorb heat in the daytime and radiate it out at night. If it is not frosty it will be cold wet and cloudy. Growth will be slow and there are few flowers out. There is not a lot to do in the terrestrial house.
Pterostylis robusta and Acianthus pusillus flower this month. If there are no flowers this year, they probably aborted due to high temperatures or excessive dryness over summer/autumn. Try putting the pots under the bench in a cooler position next summer.
The last of the terrestrial orchid leaves should appear this month although there are always a few stragglers. Tubers that formed in the bottom of a pot have a long way to grow to reach the surface. Sometimes they come out the drainage holes. If no plants appear, do not throw the pot away. Sometimes orchids take a year off and send up a leaf the following year. They are capable of forming a new tuber from the old without making a leaf. Gather together the “empty” pots in a corner. They can be left for another year or you can knock them out next month to try to establish what can be improved. Most weeds have germinated by now so weeding gets easier.
It is hard to drag yourself away from the heater this month but at least once a week go out on a wet night with a torch and examine your orchids for slugs, snails, earwigs, cockroaches, grubs and beetles. They always feed on your best orchid buds.
The SAROC Fair is in June. Clean up your flowering pots for the NOSSA stand. Other orchid clubs hold winter shows in June & July. Go along and see if there are any interesting terrestrials on the trading table.
Watering When: cauline type Pterostylis
A common question asked is when to water terrestrials. The short answer is to keep them dry over summer but there are variations such as was previously posted about the watering regime for Chiloglottis. In the March 2017 NOSSA Journal, Les Nesbitt’s article highlights another watering variation.
Jane Higgs’ lovely pot of the red form of Pterostylis coccina in flower had a blue tag. Jane explained that a blue tag meant that watering had to commence in January for that pot and not at the end of February as is normal for most terrestrials. Start watering later and there will be no flowers. Her pots are under a solid roof. She explained that in the ANOS Vic cultural booklet (Cultivation of Australian Native Orchids) there is a list of cauline type greenhoods which she tags with blue, and includes Pterostylis decurva, aestiva, laxa, coccina, revoluta, reflexa, truncata, robusta, alata, and fischii. To this list can be added abrupta and also the rosette types ophioglossa and baptistii which shoot early.
I have trouble growing and flowering this group of Autumn flowering greenhoods. I went home and dragged out my ANOS Vic booklet and brushed up on the notes. I found several old blue labels in the shed and cut them into strips. I now have blue labels in my pots and the pots are grouped together in the shadehouse where they get afternoon shade. They were given a thorough watering but it will be too late to expect flowers this year. I find large tubers of this group rot easily in Spring and the plants go dormant earlier than other greenhoods. I will try to remember to move the pots under cover in September to let them dry off.
Having a visual reminder would certainly make it easier to know when and which pots to water. Obviously other coloured tags can be used instead of blue, so long as they stand out from the label.
Genes, seasonal conditions or pure chance?
Leo Davis is an orchid hunter. He is meticulous in his observations and notes details that many of us may miss. In this article he muses upon the variations that he sees in the field.
You, as I do, must occasionally come upon an orchid or an orchid event that is a little outside normal experience. When I do, I wonder whether this is a purely chance event or is it caused by recent local environmental factors, or is it due to the genes of the plants. Or a combination of these?
I’ve been watching a couple of patches of fire orchids (Pyrorchis nigricans) that many of you will be familiar with, one at Knott Hill N.F.R., the other at Monarto C.P., where a few plants flower every year, without the normally required stimulation by fire. I need to check whether it is the same plants that flower each year.
The tall leek orchid (Prasophyllum elatum) puts up leaves at Scott Creek C.P. every year but does not flower. A fire swept through in early 2014 and most plants flowered in October. They’ve not flowered since. But over at Ramsay Way, west of Pt. Vincent, a few plants flower each year without fire. I assume genes are involved.
In April 2014 I chanced upon a patch of Adelaide Hills parson’s bands (Eriochilus collinus), along Moore’s Road, at Morialta C.P., in which the majority of plants had three flowers per stem. Was this because of favourable conditions or genes? Over the next two seasons I saw only the occasional double header and mainly single flowered plants. I will continue observations and records.
In July 2015 I found a dense patch, about 3 m2 in area, of hundreds the common mallee shell orchid (Diplodium dolichochilum), in Ferries-McDonald C.P. As usual less than ten plants were in flower, but two of them were double headers. I’ll be checking this season and expect this not to be a chance event but one due to genes.
On May 27, 2012, Bob Bates led a NOSSA outing to Scott Creek C.P. and as ever, when he leads, we saw and learned a lot. He showed us a patch of fringed hare-orchids (Leporella fimbriata) that he assured us should not be growing there on that steep rocky site and that the plants would not flower most years. Unfortunately he was right, as usual. I could not find plants in 2013 and 2014 and it took three searches in 2015 to find a very few leaves. On May 10 this year, over an area of less than 10 m2, I found perhaps 50 leaves and just seven plants in flower. Three of these had three flowers and a tiny unopened bud (check the photo) and the others were doubles. I’ve never seen a triple flowered plant in hundreds I’ve seen at Knott Hill N.F.R. Are genes in an isolated population at play here? Given the paucity of flowering at this site, it may take me years to sort this one out.
Do Any Orchids Grow Near The Sea?
Orchids are found in a wide range of habitats. One such habitat is the littoral zone or more simply the seaside. The following information is taken from the NOSSA’s CD/DVD South Australia’s Native Orchids 2011.
The Littoral Zone
Many orchid species have a linear distribution following the coastline. Here on the leeward side of sandhills the air is usually moist and mild, few frosts occur so close to the sea and sea-fogs in winter will cause water to drip into the sand which easily soaks up both the moisture and the extra nutrients provided by sea-spray. Some of the best known coastal orchids include the gnats Cyrtostylis robusta, pink fairies Caladenia latifolia, coast onion-orchids, Microtis arenaria and coastal helmet orchids Corysanthes expansa as well as C. despectans. All of these are colony forming species, mostly because the windblown sand would soon cover ‘single plant’ species which start to appear after the second line of dunes.
Coastal species can be a few kilometres from the sea but there are several that grow either at the high tide mark, within sight or sound of the sea or in coastal dunes. Apart from the ones already mentioned above, the following are some others that can potentially be found within sight and sound of the sea.
- Acianthus pusillus (Mosquito Orchid)
- Arachnorchis cardiochila (Thick Lipped Spider Orchid)
- Arachnorchis fragrantissima (Scented Spider Orchid)
- Arachnorchis fuliginosa (Coastal Spider Orchid)
- Arachnorchis sp Brown Bayonets (Port Lincoln Spider Orchid)
- Bunochilus flavovirens (Coastal Banded Greenhood)
- Bunochilus littoralis (Lake Saint Clair Banded Greenhood)
- Caladenia sp Selfing Coastal Dunes (Little Dune Fingers)
- Corunastylis nigricans (Port Lincoln Midge Orchid)
- Diuris orientis (Wallflower Orchid or Bulldogs)
- Diplodium erythroconchum (Red shell Orchid)
- Glossodia major (Waxlip or Purple Cockatoo Orchid)
- Leptoceras menziesii (Hare Orchid, Rabbit Ears)
- Prasophyllum elatum (Tall Leek Orchid)
- Prasophyllum litorale (Vivid Leek Orchid)
- Prasophyllum sp Late Coastal Dunes
- Pterostylis cucullata (Leafy Greenhood)
- Pterostylis curta (Blunt Greenhood)
- Thelymitra antennifera (Rabbit Ears; Lemon Sun Orchid)
Unfortunately, where there has been settlement, it is now unusual to find these species so close to the sea.
2015 June Winning Photograph
Of the five entries this month, four featured winter orchids. Lorraine Badger entered a Diplodium robustum, whilst Claire Chesson, Robert and Rosalie Lawrence all entered Urochilus sangineus. Though not the winning photographs it was interesting to see the differences between the U. sangineus with one being no taller than the small Acianthus pusillus next to it and another being taller than the rapier sedge.
But the winning photograph was the spring flowering Arachnorchis argocalla (White Beauty Spider Orchid) by Pauline Meyers. This is amongst our most threatened orchids and is dealt with in depth in the Recovery Plan For Twelve Threatened Orchids in the Lofty Block Region of South Australia 2010. This fungi dependent endemic orchid is rated Endangered both at State and National level.
Found in the Southern and Northern Lofty regions, it range has been severely reduced by possibly 80%. Since 1918 no plant has been found south of Adelaide.
Flowering from September to October, it is often found in grassy woodlands often growing on gentle southerly-facing hill slopes. The soil is a clay loam with a high humus content.
This beautiful orchid has one to two non-perfumed white flowers with thickened but not clubbed drooping lateral sepals and petals. The strongly recurved broad labellum is usually white, sometimes crimson, fringed with short teeth.
This is one of our larger spider orchids reaching a height of 60cms. The size of the plant flower and leaf help to distinguish it from other similar appearing orchids such as A. brumalis and albino flowers of A. behrii.
Like many of the spider orchids it takes 2 – 5 years to reach maturity and then has a potential reproductive life of 10 years. With an average pollination rate of less than 10%, the potential to increase the population is low and any threat to survival of the individual plants needs to taken seriously.
Some threats are obvious such as weed invasion including the garden escapees such as Topped lavender (Lavandula stoechas spp. stoechas) and action is being taken to curb the spread of weeds through targeted weeding programs.
Another threat is habitat loss. This has been the result of land clearing but sites are being protected either through conservation legislation or Heritage Agreements. Habitat loss can also occur indirectly and that is through Phytophthora being introduced into the sites. Although the direct effect of Phytophtora on the orchid is unknown, it is known that it can affect the plants that grow in association with this orchid. This threat can be reduced by all of us implementing good hygiene practices.
These were some of the threats noted in the Recovery Plan. This plan was not just defensive, ie attempt to halt and minimalize the damage; but it was also proactive with measures outlined to increase the population. These included seed and fungi collection eventually resulting in germination and cultivation with a view to re-introduction.
It is good to see that there is a plan and active steps are being taken to bring this orchid back from threat of extinction.
Websites accessed 1 July 2015
White Beauty Spider Orchid (Caladenia argocalla) Recovery Plan
Caladenia argocalla – White-beauty spider-orchid, biodiversity species Profile and Threats Database
Recovery Plan For twelve threatened Orchids in the Lofty Block Region of South Australia
Bates R J, South Australia’s Native Orchids 2011 DVD
The Great Orchid Pretender
Actually there is more than one.
Frequently NOSSA receives a request to identify an orchid in someone’s garden. Often, instead of an orchid (but occasionally there are orchids), it is the Ariasrum vulgare (common name Friar’s Cowl Lily or Cobra Lily).
Native to Asia and Europe, notably the Mediterranean and introduced to Australia, it is often mistaken for one of the flowers of the Pterostylis (Greenhood Orchids) or Diplodium (Shell Orchids). Some have called it a Blackhood orchid others Snake Orchid. It’s resemblance to the Greenhoods and Shell Orchids is superficial as they have none of the orchid features. The dark purple hooded part is not the flower; it is a spathe (bract). The flowers are minute hidden on deep down on the “tongue”.
The hood of the orchids is the combination of a deeply concave dorsal sepal interlocking with the lateral petals; and the fusing of the two lateral sepals. Tucked away within the hood is the labellum (a modified petal) and the column (the reproductive organs of the flower). The leaves of Ariasrum are quite large and distinctly different from any of the Greenhood orchids.
Australian Orchids & the Doctors they Commemorate Part 14 of 20
Richard Sanders Rogers (1862 – 1942)
An Adelaide physician, doctor-soldier and forensic pathologist who described 82 new orchid species (66 from Australia).
Diplodium rogersii (= Pterostylis rogersii) or Curled Tongue Shell Orchid
Prasophyllum rogersii or Marsh Leek Orchid