Monthly Terrestrial Orchid Culture – April

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
Les Nesbitt

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.

Thelymitra malvina (Purple Tufted Sun-Orchid)

2019 Winning Photograph Competition

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.

1902 SM Pauley Thelymitra malvina

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

T. malvina T atronitida
Stem 3 sterile bracts 2 sterile bracts
Height 25 – 75 cms 30 – 50 cm
Flowers Slightly larger (but can have smaller flowers) Smaller flowers
Inflorescence 3 – 25 usually loose 2 – 8 ( – 16)
Column 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.

REFERENCES

Bates RJ, 2011 South Australia’s Native Orchids, electronic

Backhouse G, Bush Gems, A Guide to the Wild Orchids of Victoria, Australia, 2016, electronic

VicFlora, https://vicflora.rbg.vic.gov.au/flora/taxon/0de4b1c5-3f1f-43ea-9464-c713a12d5758 Accessed 6 March 2019

VicFlora, https://vicflora.rbg.vic.gov.au/flora/taxon/748b23b6-4779-4a93-89fc-8ec2a8b05a06  Accessed 6 March 2019

Atlas of Living Australia, https://bie.ala.org.au/species/NZOR-4-76548  Accessed 6 March 2019

New Zealand Native Orchids, https://www.nativeorchids.co.nz/Descriptions/Thelymitra_malvina.html Accessed 6 March 2019

Jeanes J, 2013 An overview of the Thelymitra nuda (Orchidaceae) complex in Australia including the description of six new species https://www.rbg.vic.gov.au/documents/MuelleriaVol-31-p3-Jeanes-PDF-Accessibility.pdf Accessed 6 March 2019

Natural Value Atlas, https://www.naturalvaluesatlas.tas.gov.au/downloadattachment?id=14596  Accessed 6 March 2019

Monthly Terrestrial Orchid Culture—March

As stated last month, this is the second in the series of terrestrial culture notes for growing orchids in Adelaide.

Terrestrial Culture—March

Les Nesbitt

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 Eriochilus cucullatus 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.

Eriochilus collinus
Eriochilus collinus (syn Eriochilus sp Adelaide Hills, Eriochilus aff cucullatus)

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.

Diuris tricolour in flask

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.

food healthy nature forest
Photo by PhotoMIX Ltd. on Pexels.com

Good News, They’re Back …

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.Plants Return to Park

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.

Monthly Terrestrial Orchid Culture – February

The following article by Les Nesbitt is from Journal of the Native Orchid Society of South Australia, February 2019 Volume 33 No 1. It is the first of a monthly series that Les is planning to produce for this year.

It should be noted that February in Australia is late summer and dry; and that this article has been written for Adelaide growing conditions. Many of the terrestrial orchids have been dormant.

Terrestrial Culture — February

The excitement is building with the new growing season about to commence. First leaves on the early species may show this month so start looking. Look with your eyes not your finger. Many a new shoot has been broken by that dastardly finger. Keep the blue tag pots moist. Blue tag orchids include Diplodiums, Ptst. baptistii and Corybas hispidus, all species from the East Coast of Australia.

Repotting and Watering

Finish repotting as soon as possible. Many tubers start shooting this month and are easily damaged by handling. Move all pots to their growing positions for the coming winter. For local orchids adapted to a dry January-March, commence watering in the last week of February and increase watering in March. The water will run down the side of a dry pot and out the drainage holes leaving a dry plug of mix in the middle where the tubers are. Watering three days in a row should wet the pot right through. Continue light watering weekly, so pots do not dry out completely again. Top up the cut she-oak needle layer on pots as needed. This is very important for the fungus dependent species which do not get repotted often.

Diuris tricolour in pot
Topped with she-oak cuttings

Hunting the Grubs and Slugs


Start the nightly visits to pick off the slugs, snails, earwigs and grubs. Hunts are more successful on cooler nights after rain or watering. If the new shoots get eaten off as soon as they appear you might not even see them and wonder why your orchids did not come up.

Labelling

If the names on labels are starting to fade rewrite them before the name is lost. Remember to pot up any spare tubers for raffles, stalls and the tuber bank later in the year.

Diplodium


The cauline group of greenhoods (Diplodium) from the eastern states are the first to shoot and ideally should have blue tags and have been repotted in January with watering commencing at the end of January. There are some 38 species in this group. Some come from high altitudes in NSW/Vic and start flowering there in February. They flower in March/April/May in Adelaide.

Diplodium in cultivation
Diplodium robustum – one of the cauline greenhoods, with both flowering and non-flowering plants


Points to note about Diplodiums:

  • Flowering plants look different to non-flowering plants. Flowering plants have small pointed leaves on the flower stem. Nonflowering plants have a rosette of rounded leaves flat on the ground. Usually there are only a small percentage of flowering plants.
  • They flower early in the growing season. Most flower in autumn with a few stragglers in winter. None flower in spring.
  • The rosette plants multiply and are easy to grow in regular terrestrial mixes. New tubers form in Autumn.
  • Diplodiums are not easy to flower in Adelaide. Flowers abort if too hot and/or too dry. Grow them in the coolest shady area there is. Keep pots shaded until late March. Local species are easier to flower as they flower in winter.
  • Poor tuber development from flowering plants is common. These plants sometimes die after flowering.
  • Flowering plants can be tall & slender and may need supporting with a wire cylinder. Stakes can damage the developing new tubers.

 

For additional information on growing terrestrial orchids click here 

What makes an Orchid and Orchid?

Orchid flowers are extremely variable in appearance, ranging from mimicking spiders, flying ducks, helmets, ants, etc. This variety also can cause some confusion. People have mistaken a different type of flower for an orchid and vis a versa.

This raises the question of what makes an orchid an orchid? With so much variety, how can they possibly belong to the same family?

Using orchids found in the Adelaide Hills, the following video shows three key features that helps identify a flower as an orchid. These three features are found in all orchids worldwide.

So watch and enjoy …

Waiting for the rain …

Last year we waited for the rain. The rain heralds the start of the orchid season. Last year the season was dry, very dry. It was below average and it was hot.

So how did the orchids fare in the Adelaide Hills? The start of the season was slow with our first field trip not being until May 26 because of the lack of rain.

At the time, the smallness of the plants was noticeable with one specimen of flowering Leporella fimbriata standing no more than 2 cms. Normally  the flower stem can be up to 25 cms tall. This trend of smaller plants continued throughout the year.

The following two photographs show the difference in size.

Small Leporella fimbriata
A miniscule Leporella fimbriata near an ant nest

Leporella fimbriata sm

And on January 28, we came across the smallest flowering Dipodium pardalinum that we’d ever seen. Normally, this genus can grow up to about 100 cms in height but this one barely reached above the height of Robert’s shoe, ie, about 10 cms. True this was an exception but overall there not many plants, and even they were spindly and small in comparisons with previous years.

Below are two photographs illustrating the size difference

Small Dipodium pardalinum
A very tiny Dipodium pardalinum

Dipodium roseum
An average sized Dipodium

So what is the outlook for orchids for 2019? That will depend upon the rains.

When does the orchid season get going? Again that depends upon the rain but expect to see the autumn orchids about six to eight weeks after a good rain episode.

So we wait for the rains ….

Sarcs – Growing without the Nonsense!

The following article is from Volume 42 Number 10 November 2018 Native Orchid of South Australia Journal. Marg Paech, editor, has written an excellent summary based upon Kevin Western’s detailed notes which he has kindly supplied and is available here.

1510 sarcochilus cropped

Kevin Western, this month’s guest speaker didn’t hold back. He exposed some of the myths pedaled by good growers who misinform naive newbies or other growers.
Until about 1960 or thereabouts, the only Sarcochilus orchids that existed were in the bush where they had evolved and grown for all time and the only orchids that existed in people’s collection were bush collected so therefore all were species. No doubt, at times in the bush, there were hybrids made accidentally by pollinators or by other natural chance events. 1968 was the first time we can say for sure that there were hybrid Sarcochilus in existence.

Sarcochilus are native to the east coast of Australian and to Tasmania. There are about 25 species recognized and the number has grown recently with the splitting off of S. minutoflos.

The easiest species to grow for hobbyists generally are Sarcochilus hartmannii and S. fitzgeraldii. From their physical appearance and flowering time, flower shape and nature, it can be seen that they are closely related. Their natural environment can be matched in a pot by using a range of different potting materials (either solely or a mixture of) – suitable size pine bark, Perlite, cut up tree fern fibre, rice hulls and or sphagnum moss. Remember, they will grow on rocks, rubble or on various types of natural and artificial mounts!

03 KK sm Sarcochilus falcatus Mt Banda Banda
Sarcochilus falcatus

Humidity

Sarcochilus grow naturally where they do because of the balance between the suitable amount of reliable moisture in the form of rainfall and or dew; and those unavoidable moisture losses due to sun, heat and wind. We can replicate that by just giving our Sarcochilus regular waterings, and ensuring that our potting medium is coarse enough. An extra layer of shade in really hot summers can help, and by reducing wind movement by the location and provision of shade houses, we can create suitable growing conditions for our orchids. Frequent watering is the trick – retirees by hand watering and workers by sprinklers, misters on timers or thermostats or similar. Air movement is a must but here in sunny Adelaide we get plenty of it and in fact, too much movement has a drying effect.

Potting Mixes

The best mix for Cymbidium (sic)* orchids is a coarse, non-retentive medium – far better because they can be watered frequently – even twice a day or far more, and plants do far better. Even standing the pots in water during summer works wonders! Trial and error is the best way to learn, as experienced by Kevin.

Sarcochilus can be potted into clay balls used by hydroponics growers. Good, clean coarse pine bark also is fine.

1510 sarcochilus x velvet

Watering and Fertiliser

It is generally considered impossible to grow plants on mounts in shade houses etc in suburban Adelaide. Yet another myth! They grow exceptionally well, a fact that Kevin found out thanks to Kris Kopiki. It is more difficult to overwater a plant on a mount.

There are lots of myths about fertilizing. Using far more dilute fertilizer applied to a dryish mix and roots, Kevin has found to be far more effective. His policy is to fertilise weakly and frequently. Despite the hundreds of fertiliser options and brands available – they all are only better or worse
sources of those few essential substances which an orchid requires. The seaweed extract products are probably good as they seem to promote root growth. Keep it simple is the best option.

Summary

Our Sarcochilus have roots designed to grow attached to rocks or branches or twigs and are designed to catch and hold quite small water opportunities and they may benefit from drying out from time to time and for periods of time.

Coarser and less water retentive media are advantageous by enabling the roots to experience some drying as would occur in nature.

We are then able to water and fertilise far more often and our plants will grow better. We need to better understand what our preferred fertiliser’s strengths and weaknesses are so that we can better supply their needs more simply, more effectively and at lower cost.

Regular watering, wind control and shade improvement to avoid drying stress is far more sensible than hoping to reproduce and sustain high humidity.

Thank you Kevin for such a candid, down-to-earth talk full of good advice for growers

*In Kevin’s note he discusses his experience with Cymbidiums but Sarcochilus can also be grown with a similar medium.

sarco nugget gold rush seedling (1)edited

Selecting Photographs for 2019 NOSSA Calendar

Every year, NOSSA holds monthly photograph competitions. This year, NOSSA decided to give the entrants an opportunity for their photographs to appear on a calendar. There have been 51 entries this year, so we are asking people to vote for the twelve images that they would like to see in a calendar.

To vote

  • Select the numbers corresponding to the twelve images that you would most like to see in your calendar
  • Indicate if you are interested in purchasing a calendar
  • Email – nossa.enquiries@gmail.com  (Subject Heading – Calendar)
  • Voting closes on Thursday 1 November 2018

The results will be collated to determine the twelve most popular images will go into the calendar. We plan to have the calendars available for purchase at the next meeting, Tuesday 27 November.

If you would like more details or see the images in a higher resolution, use the above email address to contact NOSSA.

2018 Thumbnails Photogrpahs for voting

Genus Plumatichilos

This week’s blog is from the Journal of the Native Orchid Society of South Australia, Volume 42 No 8. Leo Davis has been doing a series of articles aimed at helping members learn how to identify the orchids.

This article is about Plumatichilos, one of the segregate genera of Pterostylis. It has an unique labellum which sets it apart from the other Greenhoods. Leo wrote this article soon after David Jones named them in the Australian Orchid Review.  Will these names be accepted or not is a matter of waiting and seeing but it should be noted that they have been in manuscript form for many years. At the time of writing, they are not in the South Australian eflora.

Both the species discussed in Leo’s articles are from the Plumatiochilos plumosum complex or group.

Plumatichilos sp. Mallee Bearded Greenhood =Plumatichilos multisignatus

Plumatichilos sp. Woodland Bearded Greenhood = P. foliaceus

Unless otherwise noted, all images are Leo Davis.

Genus Plumatichilos.

Back in 1990 Bates & Weber placed all greenhood orchids in genus Pterostylis(1. pp118-143) where some of you and all Australian State Herbaria and certainly Janes & Duretto (3. pp260-269) would have them still be.  In 2001 Szlachetko erected the genus Plumatichilos.  In his Guide(4. pp286-339), Jones divided the greenhoods into 16 separate genera, these in two groups, each of eight genera.  One group all have the lateral sepals directed downwards (including Bunochilus and Urochilus) and the other eight all have them directed upwards (deflexed, as in Diplodium and Pterostylis).  Even those of you who reject the splitting and creation of the extra genera will concede that those placed in Plumatichilos, which have downward directed and partly fused lateral sepals (forming a synsepalum), are strikingly different in appearance to any other Pterostylis species.  The most obvious distinguishing features are the unique labellum and the two openings to the galea.

I had known just two species of Plumatichilos, both of which were undescribed.  I could recognise and distinguish them essentially because they grew in very different habitats and locations.  I used Bates’ tag names, Mallee Bearded Greenhood (Plumatichilos sp. Mallee Bearded Greenhood) (3. pp913-4) and Woodland Plumed or Bearded Greenhood (Plumatichilos sp. Woodland Bearded Greenhood)(1. pp915-916).   In recent weeks both (along with two other South Australian species) have been formally described.  They are now, respectively, Plumatichilos multisignatus(5. pp33-35) (Fig. 1) and P. foliaceus(5. pp30-32) (Fig. 2).  But, to a large extent, I still identify them more by the locations in which I find them than, to my eye, clearly discernable physical features.

Fig 1 P multisignatus Fig 2 P foliaceus
Fig. 1. Plumatichilos multisignatus. Monarto. Sept 10, 2012. Fig 2. Plumatichilos foliaceus. Para Wirra. Sept 11, 2013.

I had no idea what ‘barrier trichomes’ were but I saw that Jones listed them as the last of 13 dot pointed characters of genus Plumatichilos(5. p26).  Trichome simply means a hair growing from a plant epidermis.  They can be unicellar or multicellular and branched or unbranched.  The ‘barrier’ refers to its capacity to block and direct a pollinating insect to an exit path that puts it in the right posture to transfer a pollinium to the stigma (sticky receptive female part of flower).

Fig 3 Bunochilus prasinus June Niejalke Janes & Duretto, who reject the splitting of genus Pterostylis, divide it into two subgenera using the absence (subgenus Pterostylis) or the presence (subgenus Oligochaetochilus) of barrier trichomes on the column wings(3. pp262).  They place what I call Plumatichilos in the section V, Catochilus, of subgenus 2 Oligochaetochilus(3. pp266), and, yes, I see your eyes glaze over.  To them the Adelaide Hills ‘plum’ would be Pterostylis, subg. 2 Oligochaetochilus, Sec. V. Catochilus, species foliaceus.  Learning what ‘barrier trichomes’ are had me go back searching my photo library and I found images of the barrier trichomes in Bunochilus flowers that I had not previously spotted.  I have used and annotated a detail sent to me by June Niejalke. (see Fig. 3).

Fig. 3. Bunochilus prasinus. Sherlock (Type location for the species). Photo by June Niejalke.

As with all ‘true’ Pterostylis, the dorsal sepal and the two lateral petals, of the upside down flowers, are formed into a galea or cap (Fig. 1).  They are fused so closely that it can be hard to discern the join between the sepal and the comparatively small petals, especially in some less clearly striped flowers. (Figs. 1 & 2).

The typical Pterostylis galea has a single opening but in Plumatichilos there are two, a lower one, from which the uniquely formed labellum protrudes (and through which the pollinating male gnats enter) and an upper one (through which the pollinators exit) (4. p335), guided by the barrier trichomes (Fig. 4).  Through this upper opening you can observe the top of the column, including parts of it, the pollinia, the barrier trichomes, column arms and sometimes the stigma.  Two crossed filaments, in front to the pollinia, are column arms.

Fig. 4. Plumatichilos foliaceus. Scott Creek C.P. Sept 2015.

Fig 4 P foliaceus

 

Fig 5 P foliaceus.jpg The labellum (the modified third petal) (Figs 1, 2 & 5) is unlike that of any other Pterostylis sp.  It has a slightly flattened filament having a reddish-brown apical knob and two or three types of hairs along its length.  Jones describes the labellum of P. foliaceus as having three types of hairs(5. p30).  You may be able to see the short white ones (1 mm) at the base of the labellum in Fig. 5.  The longer (5-7 mm) yellow ones along the most of the length of the labellum are easy to see.  I am not sure that I can distinguish the shorter proximal (near point of attachment) yellow ones (1.5 mm).  In P. multisignatus Jones describes just two types of labellum hairs(5. p33) with the white basal ones absent, and two sorts yellow hairs, proximal ones to 1.2 mm and longer ones 5-8 mm.  To my eye, this character, two or three types of labellum hairs, is the only objective, rather than subjective , distinguishing feature between the two species that I regularly observe.

Fig. 5. Plumatichilos foliaceus. Scott Creek C.P. Sept 26, 2015.

In Fig. 5, I think that you can see that the hairs arise, in two parallel rows, not paired, from the sides of the flattened shaft of the labellum filament.

Fig 6 P foliaceus Fig. 6. Plumatichilos foliaceus in early bud. Scott Creek C.P. August 29, 2018.

Another generic character is ‘leaves sessile (no stems), ascending to erect, often with whitish or yellowish interveinal areas.’ (5. p26)  You may need to look very closely, in Fig. 6, to see these ‘windows’, mainly at the bases of the stemless leaves. 

 

References:

  1. Bates, R.J (2011). South Australian Native Orchids, DVD Issued by the Subediting Committee (NOSSA) on behalf of the
    Native Orchid Society of South Australia Incorporated.
    2. Bates, R.J. & Weber. J.Z (1990). Orchids of South Australia, A. B. Caudell, Government Printer, South Australia.
  2. Janes, J.K. & Duretto, M.F. (2010), A new classification for subtribe Pterostylidinae (Orchidaceae), reaffirming
    Pterostylis in the broad sense. Australian Systematic Botany, 23, 260–269.
  3. Jones, D.L. (2006), A Complete Guide to the Native Orchids of Australia, Reed New Holland, Australia.
    5. Jones, D.L. (2018), Six new species of Plumatichilos (Orchidaceae: Pterostylidinae) fromSouth-eastern Australia and a
    new species from New Zealand, Australian Orchid Review 83(4): 26-44.

Other articles about Plumatochilos can be found here and here.