Banded Greenhoods Bundled Together

Here in South Australia we often have only one or two species of a complex or a genus but this is not necessarily the case in the rest of the country. One such instance is Urochilus sanguineus (syn Pterostylis sanguinea) or Maroon Banded Greenhood. It is possible that we may have a subspecies or possibly the Mallee form but nothing like the occurrence of  this species in Western Australia where it is but one of many in a complex of several – the Pterostylis vittata complex or Banded Greenhoods*.

Below, with permission, is Andrew Brown’s post on Facebook with notes and images about the complex as it is understood in Western Australia.

The Banded Greenhood complex in Western Australia

Members of this complex grow 150 to 450 mm high and have up to 20 green, brown or reddish-brown white banded flowers characterised by their, short, broad lateral sepals which are joined at the base and a small, insect-like labellum which flicks up when touched. In all species, flowering plants lack a basal rosette of leaves while non-flowering plants have a flattened, ground hugging, rosette of leaves.

Banded greenhoods are found over a wide geographic range between Binnu north of Geraldton and Eyre on the Great Australia Bight, growing in shrublands, woodlands, forests and shallow soil pockets on granite outcrops.

There are ten Western Australian species in this complex, seven of which are formally named. However, as two were named as species of Urochilus, a genus not recognised in Western Australia, only five of these names are currently recognised here. In Western Australia, all members of the complex are considered to be in the genus Pterostylis.

All are winter flowering.

Pterostylis concava

Pterostylis concava AB

Distinguished from other members of the complex by its prominently cupped lateral sepals and the upturned projection near the base of the labellum. Found between Bindoon and Mt Barker.

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Pterostylis crebriflora

Pterostylis crebriflora AB.jpg

Distinguished from the similar Pterostylis sanguinea by its often shorter stature and slightly larger flowers which are crowded in a dense spike near the top of the stem. Found on the Darling Scarp near Perth.

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Pterostylis sanguinea

Pterostylis sanguinea AB.jpg

A very common species that is also found in South Australia, Tasmania and Victoria. It was named from specimens collected in South Australia. The species is similar to Pterostylis crebriflora but is usually taller with smaller, more widely spaced flowers. Flower colour is variable and it is not uncommon to find brown and green flowered forms growing alongside one another. Found over a wide area between Mullewa and Eyre on the Great Australian Bight.

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Pterostylis sanguinea (Mallee form)

Pterostylis sanguinea mallee form AB.jpg

An unnamed member of the complex distinguished from Pterostylis sanguinea by its short stature and few flowered inflorescence. Found over a wide range from the Stirling Range to the north of Esperance.

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Pterostylis sp. Coastal

Pterostylis sp coastal AB.jpg

Some consider this to be a form of Pterostylis sp. small bands but it is usually taller with more widely spaced flowers. The sepals are also narrower and often slightly cupped. Found mostly in near coastal areas between Dongara and Bunbury. Similar looking plants have also been found further inland between Brookton and Mt Barker.

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Pterostylis sanguinea (green flowered form)

Pterostylis sanguinea green flowered form AB.jpg

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Pterostylis sargentii

Pterostylis sargentii AB

A common, widespread species, distinguished from other members of the complex by its smaller flowers and fleshy, tri-lobed, frog-like labellum. Found over a huge geographic range between Northampton and Mt Ney, north of Esperance.

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Pterostylis sp. Crowded

Pterostylis sp crowded AB

 

A widespread species named Urochilus atrosanguineus in June 2017. Distinguished from the similar Pterostylis sanguinea by its more robust habit and larger dark reddish-brown flowers. It is also similar to Pterostylis crebriflora but generally flowers earlier and has more widely spaced flowers in a longer spike. Found between Wongan Hills and Katanning with rare, scattered populations on the Swan Coastal Plain.

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Pterostylis sp. Eyre

Pterostylis sp Eyre AB

A distinctive member of the complex distinguished from others by its pale coloured flowers. Like Pterostylis sanguinea (mallee form) it has a short stature and few flowered inflorescence. Found along the coast between Toolinna Cove and Eyre on the on the Great Australian Bight.

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Pterostylis sp. small bands

Pterostylis sp small bands AB

A northern species named Urochilus orbiculatus in June 2017. It is regarded by some researchers to be a form of Pterostylis sp. coastal but is usually shorter with a more densely crowded spike of flowers. Its sepals are also broader, more rounded and flattened rather than slightly cupped. Found north of Perth between Cataby and Binnu.

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Pterostylis vittata

Pterostylis vittata AB.jpg

A widespread species distinguished from other members of the complex by its less fleshy, paler coloured, predominantly green flowers and narrower, elongated, slightly cupped sepals. The flowers also have a more translucent appearance. The typical form is found between Bindoon and Balladonia. There is a northern form with a shorter spike of often fawn coloured flowers found between Cataby and Binnu.

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It should be noted that in South Australia and Victoria U. sanguineus was originally called P. vittata but that species is now recognised as being endemic to Western Australia.

*As an aside, the common name Banded Greenhoods is used in South Australia for the subgenus Bunochilus (previously Pterostylis longifolia which is now considered endemic to New South Wales).

 

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Are there any orchids growing in the desert?

Think of deserts and the image is that of a bleak barren landscape with little to see but this is not so.  The conditions are harsh but there is a myriad, though not an abundance, of hardy fauna and flora if one but looks closely.

But concerning orchids – No orchids have been found in true deserts…..  They also appear to be absent from the arid mountains of the far north-west, or at least no-one has ever found orchids there.

Orchids need moisture and so they do not grow on unstable soils such as dry sand-hills, gibber plains or the many saline areas of the far north but on the desert fringes there are micro-climates where the moisture, humidity and soil structure is  just right (to quote Goldilocks) for orchids.  This micro-climate is created by [s]hrubland  [which] is … [an] … important dryland orchid habitat. Besides providing shade and shelter for the orchids, shrubs like the many species of wattles, Acacia and hop-bush Dodonea drop fine leaves which help to hold the soil together and slowly break down into humus rich with nutrient and water storing capability. These shrublands usually form in soils too dry or shallow for trees. Orchids of course have no need for deep soils as they are shallow rooted. 

Robert Bates Semi-arid Shrubland.jpg
Semi-arid Shrublands, Flinders Ranges

Of the five desert botanical regions, the Eastern region contains the most number of species with over a dozen species.

Botanical Regions Map
Colour added to indicate the desert regions (in red)

Orchids of the Eastern Region – this region is from the east of the Flinders Ranges to the New South Wales border and includes the Olary Spur and Lake Frome.

Arachnorchis toxochila – Dry Land Spider Orchid or Bow Lip Spider Orchid.
Corunastylis tepperi – Mallee Midge Orchid
Diplodium robustum – Common green shell-orchid.
Hymenochilus pagophilus – Mountain Shell-orchid
Microtis eremaea – Desert onion orchid
Microtis frutetorum – Common woodland onion orchid.
Oligochaetochilus bisetus species complex, Rusty rufous-hoods

Oligochaetochilus sp. Blue-bush Plain – Blue Bush rufous-hood (O. bisetus complex)

Oligochaetochilus sp. Outback – Outback rufous-hood (O. bisetus complex)

Oligochaetochilus cobarensis – Little desert rufous-hood
Oligochaetochilus sp. Crossed Sepals Bibliando rufous-hood. (O. hamatus complex)
Oligochaetochilus sp. Bimbowrie Bimbowrie Rufoushood (O boormanii complex)
Oligochaetochilus linguus – Swept-back Rufoushood

Oligochaetochilus sp. Old Boolcoomatta Large-lip rufous-hood (O. linguus complex)

Oligochaetochilus sp. Quartz – Quartz hill rufous-hood (O. linguus complex)

Oligochaetochilus sp. Slender desert – Slender Desert rufous-hood (O excelusus complex)
Undescribed not within any other Oligochaetochilus complex

Oligochaetochilus sp. Canegrass – Desert Sand-hill Orchid.

Oligochaetochilus sp. Oratan Rock – Diminutive rufous-hood

Oligochaetochilus sp. ‘Mt Victoria Uranium Mine’ – Uranium rufous-hood

Prasophyllum odoratum – Scented Leek-orchid

Prasophyllum sp. Desert Desert Leek-orchid (P. odoratum complex)

The Gairdner-Torrens region includes, besides the salt lakes it is named after, the Gawler Ranges and the southern part of the Great Victoria Desert.  Though not as many species as the Eastern region, it contains some different species including a Sun Orchid.

Thelymitra megcalyptra
Thelymitra megcalyptra
Arachnorchis interanea – Inland Green-comb Spider Orchid
Arachnorchis toxochila – Dry Land Spider Orchid or Bow Lip Spider Orchid.
Hymenochilus pagophilus – Mountain Shell-orchid
Hymenochilus pisinnus – Tiny Shell-orchid
Jonesiopsis capillata – Pale Wispy Spider Orchid
Linguella sp. Hills nana – White haired little-greenhood.
Microtis eremaea – Desert onion orchid
Oligochaetochilus ovatus – Ovate Lip Rufoushood
Oligochaetochilus xerophilus – Desert rufous-hood
Prasophyllum sp. Desert Desert Leek-orchid (P. odoratum complex)
Thelymitra megcalyptra – Scented or Dryland Sun Orchid

Third of this group is the Nullabor region.  Consisting of flat treeless limestone plains, this area, surprisingly, has two species both of which have been found close to the coast.

Urochilus sanguineus – Maroon banded greenhood
Corunastylis sp. Intermediate – Halbury Midge Orchid (C. rufa complex)
Urochilus sanguineus
Urochilus sanguineus

The final two regions Lake Eyre and North-Western contain the vast expanses of desert of the far north of South Australia.  Definitely not a place to find orchids yet one specimen has been collected from each of these two regions.

Oligochaetochilus sp. Everard Range (L. Scott 173), Mimili Orchid (possibly O. woollsii complex) from North-Western Region.

Oligochaetochilus sp. Gammon Range (O excelusus complex) from the Lake Eyre region.

It is unusual to find orchids in the desert because they only grow when there have been good winter rains which isn’t very often.  But nevertheless, here in South Australia we have over 20 possible species – an astonishingly high number for such a harsh area!

Reference:

Bates R J ed, South Australia’s Native Orchids, 2011 Native Orchid Society of South Australia

Map adapted from Flora of South Australia, Fourth Edition, 1986

 

 

2015 June Winning Photograph

06 sm PM Arachnorchis argocallaOf 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.

June 2015 other entrants
Photographers from L to R: Claire Chesson, Rosalie Lawrence, Lorraine Badger, Robert Lawrence

References

Websites accessed 1 July 2015

White Beauty Spider Orchid (Caladenia argocalla) Recovery Plan
http://www.environment.gov.au/archive/biodiversity/threatened/publications/recovery/c-argocalla/index.html
Caladenia argocalla – White-beauty spider-orchid, biodiversity species Profile and Threats Database
http://www.environment.gov.au/cgi-bin/sprat/public/publicspecies.pl?taxon_id=54991
Recovery Plan For twelve threatened Orchids in the Lofty Block Region of South Australia
http://www.environment.gov.au/system/files/resources/e362cfd2-a37b-443a-b007-db3a2b7b64dd/files/lofty-block-orchids-recovery-plan.pdf

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

Greenhood Pollination Strategy

Since orchids, and Australian orchids in particular, first came to the attention of the western world in the 1800s researchers have been fascinated by the so many different aspects of the orchid’s morphology and life cycle. One area of interest has been that of how orchids are pollinated. The mechanism of pollination has not always been clear as the orchids seem to use different and complex methods.  From time to time various papers have been published of observations by researchers.

One such paper was published in the Annals of Botany 113: 629 – 641, 2014 titled ‘Caught in the act: pollination of sexually deceptive trap-flowers by fungus gnats in Pterostylis (Orchidaceae)’ by R D Phillips, D Scaccabarozzi, B A Retter, C Hayes, G Brown, K W Dixon and R Peakall.

The ‘question and answer’ style of the paper helps with ease of reading and is worthwhile perusing, even for the lay person. The accompanying VIDEO is also of interest.

The essence of the paper was to establish whether sexual deception was used to facilitate pollination.  The species researched was Pterostylis sanguinea (syn. Urochilus sanguineus) and the researchers confirmed that this did happen.  Their research showed that the attraction for the insect came only from the labellum which exuded an alluring chemical.  P. sanguinea has a mobile hinged labellum which is a feature of other sexually deceptive orchids such Paracaleana, Caleana, Arachnorchis.

Urochilus sanguineus RWL
Pterostylis sanguinea syn. Urochilus sanguineus with the untriggered labellum
Urochilus sanguineus RWL(1)
Pterostylis sanginea syn. Urochilus sangineus with a side view of the labellum