Pterostylis insectifera

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Pterostylis insectifera

Strangely, this plant is known from less than a dozen records that are spread over a huge area ranging from Wyalkatchem (NW of Perth) to Mardabilla on the Nullarbor a distance of nearly 900 km (560 miles); it is also recorded for the Ravensthorpe/Bremer Bay district. Despite relatively few records, this plant is not regarded as endangered because much of its distribution is in remote country that receives few visitors, so it is highly likely there would be others somewhere between the known locations.

It is a very difficult plant to spot, blending into the surrounding environment almost imperceptibly. I had pulled off a narrow unmade track to look for another plant I knew occurred there and it took me some time to notice that I had almost run over the above Pterostylis, which were only about ½ metre (20”) away from my front wheel. The colony of several plants, were growing under a eucalypt (E. salicola) amongst leaf-litter and small saltbush (Atriplex sp.).

The area where this Pterostylis occurred was on the edge of a large saltlake (Lake Sharpe, NW of Esperance) and a little above the Samphire zone, growing in a fine sand/clay/gypsum and probably alkaline soil. All plants except those photographed had finished flowering (late October) and their leaf rosettes looked to have died sometime before. Plants grow to 30 cm (12”) in height and flowering is recorded from September to October.

Pterostylis sanguinea - Dark Banded Greenhood

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Pterostylis sanguinea - Dark Banded Greenhood

Around Esperance this orchid is more common in the Mallee a little inland, although can also be encountered in coastal regions. Locally it tends to favour growing under mallee type eucalypts (as shown above), which with its dappled sunlight provides shelter from the weather and probably grazing animals like kangaroos, although it is known from other habitats elsewhere.

It is very similar to the more coastal Banded Greenhood and was classified as Pterostylis vittata until 1989. To help distinguish the two, the Dark Banded Greenhood has a very broad (almost circular) sepals, which apart from the turned up lip around its upper edge, is flattish and not dish-shaped like the Banded Greenhood. The difference is an important distinction, as this species can be quite variable color-wise and in some instances green forms are also found.

The Australian distribution of Pterostylis sanguinea is from Kalbarri 500 km (310 miles) north of Perth in WA, through the Wheatbelt (excluding the SW corner), sweeping around the southern region into SA, where common and ranging from the Eyre Peninsula to SE Victoria and even spreading to NE Tasmania where listed as rare.  http://avh.ala.org.au/occurrences/search?taxa=Pterostylis+sanguinea#mapView

Flowering in WA is recorded from June to September, but this will vary a little depending on distribution and seasonal rainfall. Locally, May to August would be more usual. 

The Pterostylis genus is listed here under Orchids.

Pterostylis sargentii - Frog Greenhood

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Pterostylis sargentii - Frog Greenhood

The Frog Greenhood orchid is mainly an inland species, commonly occurring in sheltered habitats under shrubs or between rocks in sandy loams over granite, gravel or limestone. It is found inland from Geraldton to the Stirling Range near Albany, across to the north and northeast of Esperance, then onto Norseman, to return further inland to the Geraldton region.

It mostly grows in small colonies and being around 15 cm (6”) in height with small dark flowers, it is commonly overlooked as the viewers attention is usually taken by larger and more colourful shrubs in a seldom visited location. The bent shape of the labellum (which some liken to a frog and how this plant got its common name) is unique to Pterostylis sargentii and combined with its small size and the absence of a basal rosette of leaves, it is unlikely to be confused with other species.

Flowering time is recorded from July to November, but this would be highly dependent on variable seasonal rainfall, which on average is between 20-40 cm (8”-16”) per annum, but often considerably less.

Pterostylis allantoidea - Shy Greenhood

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Pterostylis allantoidea - Shy Greenhood

This largely inland mallee greenhood is rarely seen within the Esperance region, although it is found on rocky habitats from Ravensthorpe to south of Kalgoorlie, then SE to Balladonia. However the above was photographed on a large granite outcrop called Mt. Newmont 150 km (93 miles) NE of Esperance, which is a small distribution extension for this species, although not unexpected.

A few plants in a single colony were encountered on the upper southern facing slope, growing in shallow loam between rocks and boulders, 2-3 years after a bushfire. I presume it is called the Shy Greenhood as it mostly occurs in remote locations, so is seldom seen. It appears to be rather alien when compared to other Pterostylis spp. due to the exceptionally long curved dorsal sepal, but it is not named (P. allantoidea) after that, but because of the highly irritable, sausage shaped labellum (seen in the first photo).

Flowering is recorded during August and September that also agrees with my sighting.

Pterostylis sp. ‘hairy’ - Hairy-stemmed Snail Orchid

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Pterostylis sp. ‘hairy’ - Hairy-stemmed Snail Orchid

This species is detailed in the authoritative ‘Orchids of Western Australia’ by A Brown, P Dundas, K Dixon and S Hopper and apparently apart from Mt Augustus, occurs between Cue and Balladonia. The orchids above were photographed at a large rocky outcrop shown on some maps as Mt Newmont, which is 150 km (93 miles) NE of Esperance and 85 km (53 miles) SW of Balladonia, so a small range extension.

Two colonies were seen, one on the low-lying outer granite apron, growing in a sandy loam over granite and under tall shading shrubs, whilst the other (with longer stem hairs), was facing northeast on the upper rocky slopes, so more exposed to sunlight. They grew to 15 cm (6”) in height and were openly spaced within their colony. The flowers (excluding the long vertical sepals) were around 1.5 cm (3/4”) in depth.

Flowering is recorded from June to September, which also agrees with my observations.

Pterostylis scabra - Shell Orchid

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Pterostylis scabra - Shell Orchid

In Western Australia most greenhood orchids are referred to as Snail Orchids, however there are currently 8 species known as Shell Orchids (like this species), apparently because their flowers are much larger. Pterostylis scabra apart from the flower size (over 2 cm or 1” in depth, excluding lateral sepals), has a long curved protruding labellum, plus their basal leaf rosette is quite separate from the flowering stem.

The flowers of Pterostylis scabra can be either green or bronze coloured and due to the latter is also known as the Bronze Shell Orchid, although all the plants seen above were green. There were less than 10 flowering orchids in the above small colony, but visible leaf rosettes would more than double than number. Those above are currently the only members of this species I have encountered, as they are not recorded for the Esperance region, in fact, these orchids represent a distribution extension of around 300 km (185 miles), which certainly made me wonder if I had the right species.

Distribution of Pterostylis scabra is inland from Kalbarri to Ravensthorpe a distance of over 1,000 km (620 miles), so a further 300 km extension to the east of Ravensthorpe is feasible, particularly as extensive pristine habitat exists between. (The above were discovered on the eastern portion of Namerlonia Rock, which is 15 km east of Mt. Buraminya and 28 km NW of Mt. Ragged). Another contributing factor is the Esperance region is one or more days drive from Perth, so is not commonly visited by the WA Herbarium, especially during winter when relatively few plants are flowering and limited access tracks are often boggy and treacherous.

One of the photographs above is a habitat shot and the elongated exposed granite in the lower left is where the plants were growing. They were facing east and sheltering within 30 cm (12”) of the rock, plus their habitat acquired additional moisture from rainwater run-off and seepage. The plants were to 15 cm (6”) in height and in bloom during late July, possibly delayed as this year’s winter rainfall season has been running late. Flowering elsewhere is recorded from May to August.


Update July 2013
Two photos added of new colony of over 20 plants, approximately 100 metres from the first colony.  They were growing in a more open light seepage zone over granite. 

Dwarf Shell Orchid - Pterostylis sp. 'Dwarf Shell'

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Dwarf Shell Orchid - Pterostylis sp. 'Dwarf Shell'

This is a pretty orchid around 10 cm (4”) in height, with white/brown striped flowers (about 2 cm or 3/4” long), which are noticeably narrow when compared to their length. The identification of this orchid was gleamed from the recent publication of the ‘Orchids of Western Australia’ by Andrew Brown, Pat Dundas, Kingsley Dixon and Stephen Hopper, who are well qualified in Orchidaceae. The large number of undescribed Pterostylis spp. listed on the WA Herbarium FloraBase website do not have sufficient information to make an identification, so without actually viewing herbarium specimens, this orchid book is currently the only alternative and has been extensively used in the preparation of this blog.

There was a small colony of Dwarf Shell Orchids growing in a fine brown sand/clay loam, over a low weathered granite outcrop on the edge of a small playa lake (saltlake). Surrounding this narrow granite based habitat is the much drier mallee vegetation, where the substrate is limestone instead of granite. Water from winter rainfall seeps down the gentle slope to keep this habitat moist for extended periods, thereby providing very good orchid growing conditions (see habitat photo above), which is also shared with Pterostylis sanguinea and P. vittata at this time of year.

Pterostylis sp. 'Dwarf Shell' grows under low shrubs a few metres (20 or so feet) from the dry lake, which is situated to the southeast of Mt Ridley, some 65 km (40 miles) from the coast and Esperance. Flowering is recorded from late June to September, which agrees with my July sighting.

Robust Snail Orchid - Pterostylis dilatata

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Robust Snail Orchid - Pterostylis dilatata

There are two things immediately noticeable about this orchid, the first is the flower size (excluding the thin upright lateral sepals), which is around 2 cm (3/4”) and the lack of a leaf rosette around the stem. Sometimes the basal rosette is absent all together, but if present is always to one side of the stem.

The above orchid was found around 45 km (30 miles) NNE of Esperance and SW of Mt Ridley making it further inland than other local collections, which are sketchily recorded from Munglinup to Cape Arid (near coastal and around 100 km or 62 km) east and west of Esperance. However, after a large gap to the north of Albany, it extends from there to the south of Geraldton, including several inland mallee regions.

In the Esperance mallee region, the above were part of a small colony growing under a metre (3’) high Baeckea species, in a fine brown loam over limestone. Flowering is recorded from May to August, although locally, later than May is more likely.

Spoon-lipped Rufous Greenhood - Pterostylis spathulata

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Spoon-lipped Rufous Greenhood - Pterostylis spathulata

This was an unexpected find as according to the distribution map produced by the Perth Herbarium, it is a range extension to the east of over 150 km (see update 23/12/08 below). These plants were encountered at Mt. Ridley (67 km or nearly 42 miles) NNE of Esperance.

A very distinctive orchid with nodding flowers and long fine untidy sepals that seem to point in all directions. Its name is derived from the spoon (spathulate) shaped labellum, although that is probably the last feature you would notice. Usual flowering period is during September and October.


Two well separated (several hundred metres) small colonies each of only a few plants were growing in shallow-ish soil over granite, one in the open with Borya constricta and the other under Allocasuarina huegeliana, the Granite She-oak. All plants had an aged decomposing basal rosette indicating the leaves had developed long before the flowers.

Update 23/12/08

Going on the 'Orchids of Western Australia' publication by Andrew Brown et.al., this orchid is similar to a couple of other species in the Mt Ridley region. From the description given, P. ciliata - Hairy Rufous Greenhood is most like this orchid and distinguished by the hairy sepals and petals, which the photographs above clearly show. However the habitat described for this plant is quite different "Wandoo woodland and mallee heath." Whereas the orchids I photographed were on a granite outcrop, although in a mallee area. So possibly this may be the species, but in a different habitat.

The other similar species is Pterostylis sp. 'striped' - Striped rufous Greenhood, an undescribed species that is actually recorded for Mt Ridley and is distinguished by having 'fawn-striped sepals', but there is no mention of other features, plus the flowers seem to be a little on the small side.

So I shall leave this orchid as Pterostylis spathulata until further information becomes available, as it does have a spathulate labellum and is similar in most other respects, although no mention of hairy sepals and petals is made.