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.

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Orchids In Remnant Roadside Vegetation

This week’s post written by Leo Davis is an article (slightly edited) from The South Australian Naturalist 91 (1): 34 – 37 January – June 2017. In this article, Leo highlights the importance of  the role of roadside vegetation in preserving the native orchids and flora.

All photographs are by Leo Davis.

Microsoft Word - SAN Vol. 91, No. 1, Jan-Jun 2017  pp. 34-37 OrcFig 1: Thelymitra antennifera hybrid

One of my rules of thumb is ‘If I am in a Conservation Park, I’m on ground that nobody could make a living from.’ One, usually more, of nutrient poor soils, excess salinity, extreme rockiness, steepness, poor moisture retention, low rainfall or even being waterlogged, will be a feature of the location. There are a few odd spots that have survived partly intact, that have good soil, sufficient rainfall, etc. These include cemeteries (The Nationally Critically Endangered ghost spider orchid (Caladenia (syn. Arachnorchis) intuta) holds on in a cemetery on Yorke Peninsula) or exclusion zones around water storages (including a reservoir reserve in Lobethal that the public can now access) or abandoned railway yards (including Sherlock, where so far I have found 21 species of orchids and part of a reserve in Halbury.)

Microsoft Word - SAN Vol. 91, No. 1, Jan-Jun 2017  pp. 34-37 Orc

Fig 2: Little Yellow Club Mallee Spider Orchid Caladenia (syn Arachnorchisverrucosa

When I go in search of plants with the Botany Group of the FNSSA (Field Naturalist Society of South Australia), or for orchids with NOSSA (Native Orchid Society of South Australia), or when I do surveys of threatened orchid species with DEWNR (Department Environment, Water and Natural Resources), or orchid seed collection with the Adelaide Botanic Gardens, or go on weeding parties to protect endangered species, the destination is always one of these deprived, rejected sites. The orchids I see are those adapted to or just hanging on in such sites. We never see orchids that lived on better soils, say on the Adelaide Plains. How many have become extinct?

Microsoft Word - SAN Vol. 91, No. 1, Jan-Jun 2017  pp. 34-37 Orc

Fig 3: Common Mallee Shell Orchid Pterostylis dolichochila

Wherever the land was suitable for agriculture it was clear felled. Almost nothing of the original flora and little of its associated fauna, were left. But there is a tiny flimsy exception. Crossing these highly productive agricultural zones are roads and sometimes these have remnant vegetation. For a person interested in orchids, these narrow strips are normally areas of slim pickings but occasionally finds are made. Near Halbury, the Nationally Endangered Halbury rufoushood (Pterostylis sp. Halbury or Oligochaetochilus lepidus) can be found in some roadside spots.

Microsoft Word - SAN Vol. 91, No. 1, Jan-Jun 2017  pp. 34-37 Orc

Fig 4: Mallee Bearded Greenhood Pterostylis (syn Plumatichilos) sp. Mallee Bearded Greenhood

The most remarkable piece of roadside vegetation that I have come upon was discovered by and shown to me by Glenn Dean, the Environment Officer with the City of Murray Bridge. He found a section of predominantly broombush (Melaleuca uncinata) vegetation, only about 200 m. long, on the verges of a single car sandy track, east of Murray Bridge. It is so close to the vegetation that cars can be scratched. I have found 24 species of orchid (Glenn has found more) blooming there sometime between March and October each year. All images shown here (Figs 1–11) were made at this site. If the little used road was not there the land would have been under crop, being equal in quality to regularly cropped fields to either side, and is of much higher quality than any normally allocated to Conservation Park status. Most of the orchids found can indeed be found in some of the poor sites dedicated as Conservation Parks, including species similar to those found at Ferries McDonald and Monarto Conservation Parks with their poor sandy soils. But this spot, which for some reason supports species that do not grow just 100 metres east or west along the road, has such species as the Nationally Critically Endangered Mallee Leek Orchid (Prasophyllum constrictum) (Fig. 8), that requires soils as good as those demanded by wheat, so it is essentially doomed.

Microsoft Word - SAN Vol. 91, No. 1, Jan-Jun 2017  pp. 34-37 Orc

Fig 5: Rusty Rufoushood Pterostylis biseta (syn Oligochaetochilus bisetus)

Its single plant sighting here is regarded as a ‘rediscovery’ of a species not seen for years. In the longer term I guess this tiny site of orchid species richness is in a transitory state and most species will disappear. The surrounding cropping land is neither a source of seed nor a suitable landing site for it and it provides damaging wind blown nutrients and other chemicals. So I will cherish it while it lasts and hope others appear, if only briefly. Here is a reminder, that most of you do not need, of the value of roadside vegetation (with the understanding that it can contribute to native animal mortality) and that we should manage, extend and guard its presence.

Microsoft Word - SAN Vol. 91, No. 1, Jan-Jun 2017  pp. 34-37 Orc

Fig. 6: Rufoushood Pterostylis (syn Oligochaetochilus) boormanii complex sp.

Microsoft Word - SAN Vol. 91, No. 1, Jan-Jun 2017  pp. 34-37 Orc

Fig. 7: Cinnamon Donkey Orchid Diuris palustris

Microsoft Word - SAN Vol. 91, No. 1, Jan-Jun 2017  pp. 34-37 Orc

Fig. 8: Mallee Leek Orchid Prasophyllum constrictum

Microsoft Word - SAN Vol. 91, No. 1, Jan-Jun 2017  pp. 34-37 Orc

Fig. 9: Limestone Tiny Shell Orchid Pterostylis cycnocephala
(syn Hymenochilus calcicolus)

Microsoft Word - SAN Vol. 91, No. 1, Jan-Jun 2017  pp. 34-37 Orc

Fig. 10: Caladenia (syn Jonesiopsis) capillata x Pheladenia deformis hybrid

Microsoft Word - SAN Vol. 91, No. 1, Jan-Jun 2017  pp. 34-37 Orc

Fig 11: Small Rustyhood Pterostylis pusilla (syn Oligochaetochilus pusillus)


It Finally Happened …

“The person who first records the whole pollination event will be very lucky indeed.” So wrote Bob Bates (South Australia’s Native Orchids, 2011). He was referring to the pollination event for Bearded Greenhoods in the genus Plumatichilos. As with many orchids there has always been a lot of conjecture about the pollination strategy involved so it is good to finally have photographic evidence of a previously unknown pollinator.

For several years now Rudie Kuiter, Mitchell Findlater-Smith and Rober Lindhe have been researching the relationship between orchids and insects, spending much time in the field observing and photographing the insects. Finally they have managed to obtain a photograph of a pollinator but it was not one of their photographs. Instead it was Neil Blair who took the photograph and observed a dagger fly pollinating a Plumatichilos. The male of these fascinating insects catches another insect and offers it for a nuptial gift to a female in order to be accepted as a mate. The photographs are amazing. It’s worth reading the paper Pollination of the Bearded Greenhoods (Orchidaceae) by Dagger Flies (Diptera: Empididae) just to see the pictures.

plumatochilos-sp-woodland-sm

Pterostylis plumosa: Plumatochilos plumosum

plumatochilos-sp-woodland-sm
Plumatochilos sp Woodland

 

If you are out and about this week, keep an eye out for this attractive and unusual greenhood with its bottle brush labellum and rosette of “pineapple” like leaves.

Commonly known as Woodland Plumed or Bearded Greenhood, or Plumatochilos sp. Woodland Bearded Greenhood.  The reason for the phrase name is because many consider that it is a separate species, in this instance, from Plumatochilos plumosum (syn Pterostylis plumosa).  Originally all of the Bearded Greenhood were considered as one species – Pterostylis barbata but then Leo Cady named Pterostylis plumosa as a separate species.  David Jones in his 2006 tome listed four species, P. barbatum, P plumosum, P. tasmanicum and P. turfosum.

Here in South Australia, Bates lists P. tasmanicum and two with phrase names suggesting that they are distinct from P. plumosum.

Peter Fehre recently posted on the Tasmanian Native Orchids Facebook page some helpful hints differentiating between P. tasmanicum and P. plumosum.  Very similar information is found in Bates South Australia’s Native Orchids.  These differences are:

P. tasmanicum – a short plant: short flower stem (not more than 14 cms), short labellum (to 15mm) , short ovary; short blunted galea (hood) to 25mm.  It prefers damp, sandy areas and swamp margins.

P. plumosumhas length; long flower stem (10 – 30 cm), galea to 40mm with a long tip, long labellum (to 25mm).  It is a plant of the woodlands and forests growing on well drained soil.

The differences between the two phrase named species are more subtle

References:

R J Bates, 2011, South Australia’s Native Orchids DVD, NOSSA

D L Jones , 2006, A Complete Guide to Native Orchids of Australia

September 2015 Winning Photograph

09 sm PM A ferruginea possible
Caladenia huegelii complex
Plumatichlos sp Woodland Bearded Greenhood
Plumatichlos sp Woodland Bearded Greenhood

Five photos were entered for the September competition and there was a draw, Pauline Meyers’ flower of a plant from the Caladenia hueguelii complex from Western Australia and Jill McPherson’s Plumatichilos sp. Woodland Bearded Greenhood from Scott Creek Conservation Park. The other three by Chris Davey were photographed on Yorke Peninsula (see Letter to the Editor in this September Journal).
As winners they showcase the great diversity that are found in our Australian terrestrial orchids.

Plumatichilos belongs to the greenhoods but the features that set it apart from the other greenhoods are the long thin bristled labellum, the galea pinched in the middle resulting in two openings and the rosette of leaves growing a short way up the stem. Nationally there are thought to be several species but only a small handful have been named. In South Australia, there may be a few distinct species but currently they are usually identified with a phrase name such as Plumatichilos sp Woodland Bearded Greenhood.

Mainly flowering in spring the flowers of the Caladenia huegelii complex are characterised by the thickened clubs on the three sepals, petals shorter than the long sepals, fringed (either short or long) labellum with four or more rows of calli. All of these features can be seen in Pauline’s photograph but the leaf is not so easily seen which should be long, hairy and curve inward. In all there are said to be twenty two species within this complex of which twenty are named.

References:
Brown et al (2013) Field Guide to the Orchids of Western Australia, Floreat, WA Simon Nevill Publications.
Jones, David L (2006) A complete Guide to Native Orchids of Australia, Frenchs Forest, NSW: Reed New Holland
Jeans, Jeffrey & Gary Backhouse (2006) Wild Orchids of Victoria, Seaford Vic: Aquatic Photographics.
Bates, R. J. (2011) South Australia’s Native Orchids NOSSA DVD, Adelaide