#52 A couple of winter Greenhoods

The Superb Greenhood really is a beauty. This was my first sighting, but I knew exactly what it was when I spotted it amongst the pine needles in the Watagans State Forest on the southern rim of the Hunter Valley in late July. I found only a single specimen.

Diplodium grandiflora - Superb (or Cobra) Greenhood

Diplodium grandiflora, formerly known as Pterostylis grandiflora, is commonly known as the Superb or Cobra Greenhood. Its flowering period is from May to July.

The habitat of the Superb Greenhood is amongst undergrowth on sandy soil in cool moist gullies. I found my specimen on a shaded grassy mound on the edge of a grove of introduced conifers.

It is a slender plant 15 to 25 cm high with two forms of leaves (ref: Native Plants of the Sydney District by Alan Fairley and Philip Moore). The stem-clasping (cauline) leaves are about 5 cm long and taper to an acute apex from a broad base, while a separate rosette of leaves is often absent at flowering time.

The lower sepals are erect, united in the lower third then abruptly contracting at the broad flat sinus (mouth of the flower) to 2 long points which extend high above the galea (top of the flower).

Back view of the lateral sepals

Stem-clasping leaves of the Cobra or Superb Greenhood

The Midget Greenhood (pictured below) was a great find in winter and spring of 2007 in Werakata National Park near Cessnock in the Hunter Valley. Its flowering period is July to October.

Hymenochilus muticus, Midget Greenhood, was formerly known as Pterostylis muticus. Its habitat is fairly dry open country. All my sightings were in small open patches amongst low scrub.

This orchid species varies from short and robust to about 30 cm tall and rather slender. It has small ovate to lanceolate leaves which are sometimes numerous in a basal rosette. It also has 3 to 8 closely sheathing stem bracts and a similar number of very small pale-green flowers in a spike-like raceme.

Midget Greenhood

The sepals are short and broad and joined for most of their length. They point downward exposing the short irritable labellum which has a thick dark basal appendage turned backwards.

The centre flower has the dark appendage exposed

Rosette of leaves of the Midget Greenhood

Although I haven't done much orchid hunting this year, I hope to get out and discover some more spring-flowering orchids as the warmer months approach.

More of my Greenhood Orchid posts

Blunt Greenhood - Pterostylis curta

Trim Greenhood - Taurantha concinna

Maroonhood - Pterostylis pedunculata

Tall Greenhood - Bunochilus longifolius

Nodding Greenhood - Pterostylis nutans

#35 Orchids hidden amongst the grass

Much of the appeal of Australia's ground orchids, for me, is the secretive nature of their growth habits. A single orchid plant can sway in the breeze amongst the grasses that surround it, or a few scattered plants or matted colony can be hidden by overhanging foliage. And as most don't depend upon bright colours to attract pollinators, they are often camouflaged in earthy colours of greens, browns and yellows.

Chiloglottis formicifera - Ant Orchid

I am attempting to find and record as many orchid species in the Hunter Valley as possible, so this blog entry is dedicated to describing three rather unobtrusive terrestrial orchids that I have photographed during September and October of 2007.

Chiloglottis formicifera - Ant Orchid

Chiloglottis formicifera, with the common name of Ant Orchid, is indigenous to Australia and New Zealand, but is presumed extinct in New Zealand due to over-collection. At first sight, it is a rather nondescript orchid and is therefore often overlooked. With closer inspection however, it possesses some exquisitely detailed features.

A single green and purplish-brown flower sits atop a purplish-green scape (stem) 45 to 60mm high. Two ovate, green leaves with conspicuous venation, wavy margin and short stem-clasping stalk lie flat on the ground.

Unfurling bud of Chiloglottis formicifera

The labellum is diamond-shaped with a cluster of small round calli extending to the apex, in addition to the main group of calli which has a conspicuous double-headed callus at the rear.

All Chiloglottis species are sexually deceptive. Male insects are sexually attracted to the flower by a floral scent that imitates sex pheromones of specific female insects. Pollination occurs when pollinators attempt copulation (pseudocopulation) with the flower. Here is a link to some interesting reading and images of pollination by pseudocopulation of Chiloglottis orchids.

Calli of Chiloglottis formicifera

Orchids of the Australian genus Chiloglottis are pollinated through the sexual deception of male thynnine wasps mainly from the genus Neozeleboria. Here is some further reading on the subject, and some more detailed study on sexual deception by orchids.

Flowering period is August to October, but colonies I found were finished flowering by early October. There is more information on Chiloglottis formicifera at PlantNET.

Habitat: sandy heath amongst open forest

I dismissed the following plants as 'weeds', but upon studying my books, I soon realised that I had failed to recognise what was an Onion Orchid.

Microtis parviflora - Slender Onion Orchid

Plants are entirely green with a soft stem loosely sheathed for some distance above the base by a solitary fleshy hollow leaf. The plant reaches a height of 400mm.

A spike of numerous crowded, 3mm green flowers tops the scape (stem). These flowers sit on top of a prominent swollen ovary. It is suggested by David Jones (orchid specialist) that Microtis parviflora is pollinated by ants that are attracted to the inflorescence by a sweet perfume and feed on an abundance of nectar secreted by the labellum.

Microtis parviflora - Slender Onion Orchid

Edit note: I first recorded this Microtis species as Microtis unifolia (Common Onion Orchid), but it has been pointed out to me that the labellem that is relatively heart-shaped is a feature of Microtis parviflora. Thank you to these readers who question and offer advice and alternate suggestions, for I am learning as I go.

Flowering period is October to January. I have found Slender Onion Orchids growing in white clay with grasses, as well as in cracks in rocky embankments. There is more information at PlantNET.

Leaf of a young Slender Onion Orchid

Close-up of flowers of the Slender Onion Orchid

I also overlooked these well-hidden Brown Beak orchids, but found them when I returned to closely inspect the Onion Orchids.

Lyperanthus suaveolens - Brown Beaks

This species has a stem to 300mm high sheathed at the base by a solitary erect linear-lanceolate bright green leaf. A narrow raceme of 2 to 6 purplish-brown flowers each borne in a brown bract, top the scape.

Lyperanthus suaveolens - Brown Beaks

The narrow hooded dorsal sepal extends over top of the yellow recurved labellum. I only found four plants, with flowers aged and withering. They were growing in dry white clay amongst grasses in a sunny position.

One of my books quotes the flowering period as August to September, while my other book quotes the flowering period as September to November. There is more information on Brown Beaks at PlantNET.

The stiff leaf of Lyperanthus suaveolens

Brown Beaks

Next time you're wandering through the forest, heath or unmaintained grassy areas, keep an eye out for these delightful native plants. Like me, you might be pleasantly surprised by your unexpected discoveries.

I have a linked indexed list of all orchids that I have blogged to date, making searching for specific species easy.

#32 More Spring Orchids

There are so many exceptionally beautiful and intricately detailed native plants, camouflaged amongst the undergrowth living secret lives. some of Australia's ground orchids could have been designed by the wildest imaginations for a way-out science fiction or fantasy film, so weird and complex are their flowers.

No, this is not some man-eating plant with a tentacled tongue ready to pounce. It is one of Australia's amazing orchids unfurling - Purplish Beard-orchid, Calochilus robertsonii.

I have done some serious and extremely enjoyable orchid hunting in the Hunter Valley recently, and have found some fabulous plants. It's always a thrill to 'discover' species I have not previously seen. The Copper Beard-orchid, Red Beard-orchid and Purplish Beard-orchid are three of my October finds.

Calochilus paludosus - Red Beard-orchid

When I first saw the Red Beard-orchid while walking one of the bush tracks at the Hunter Region Botanic Gardens, my excitement bubbled over. I have since seen it in the Cessnock area of the Lower Hunter Valley.

The three Beard Orchids that I'm featuring here have slight, but distinctive differences enabling them to be distinguished. The differences mainly lie in the labellum and column.

Red Beard-orchid, Calochillus paludosus has a slender whitish-green scape (stem) to about 350mm tall, with an erect, linear, three-cornered (channelled) basal leaf and 1 or 2 stem bracts. Flowers are greenish with reddish stripes. The triangular labellum (tongue or lip) bears course, crinkled red to copperish hairs and a long creased ribbon-like tail. The flower is 20 to 25mm wide.

I have found this plant growing in sandy soil amongst leaf litter in open Eucalypt forest, hard white clay, and gravel embankment. More information at PlantNET.

Red Beard-orchid (Calochilus paludosus), on the left; and Purplish Beard-orchid (Calochilus robertsonii) on the right. The most noticeable differences occur at the base of the labellum. Notice that the Purplish Beard-orchid has two dark glands (dots) at the base of the labellum, either side of crowded shiny glands. If the picture was magnified, you would notice the two prominent dark glands are connected by a raised reddish ridge. Notice that the interior of the dorsal sepal (upper back) on the Red Beard-orchid is green, while the interior dorsal sepal of the Purplish Beard-orchid is marked with vein-like reddish-purple markings.

Copper Beard-orchid (Calochilus campestris) also has the two dark glands (resembling eyes) at the base of the labellum, but is easily distinguished by the raised metallic blue or purplish markings.

This image (below) of the back of the Beard-orchid flower shows the positioning of the sepals and petals. The broad petal-shaped vertical section is the dorsal (upper back) sepal; the two stiped, horrizontal side-facing sections are the petals; and the two downwards facing sections are the lateral (side) sepals. An easy-to-follow description of the positioning of similar orchid parts can be found on my Orchid Biology blog entry.

Also noticeable in the photo above, is the creased labellum 'tail'. From my brief observations, it appears that this tail is longest in the Red Beard-orchid.

Calochilus robertsonii - Purplish Beard-orchid

I have seen more of this species than the other two. The stiff, slender, single stem is the same colour as that of the Red Beard-orchid and can be between 200 and 400mm high, with one linear, channelled green leaf. It has between 2 and 4 stem bracts.

The labellum has long lustrous purplish hairs, becoming shorter, thicker and gland-like at the base below the column. It has a relatively short, crooked strap-like 'tail'.

I have found this plant growing in grass over hard white clay, gravel embankment, moss over damp soil, and grassy soil in eucalypt forest. More information at PlantNET.

A side view of the Red Beard-orchid (Calochilus paludosus) shows the long creased 'tail' on the tip of the labellum. Although the dorsal sepal (upper back) is depressed in this instance, it is usually erect and slightly 'hooded'. Also notice one of the stem bracts.

Notice the shorter 'tail' at the tip of the labellum of the Purplish Beard-orchid (Calochilus robertsonii). Also notice that the purplish vein-like markings on the side petals are definite lines, whereas the markings on the petals of the Red Beard-orchid (above) are thicker and irregular.

And notice that the side petals of the Copper Beard-orchid (Calochilus camperstris) below appear only to have the reddish markings on the interior and not the exterior (as in the two pictures above). You will also notice the short, stumpy, crumpled 'tail' of the curled-under labellum. The differences are subtle, but important for identification purposes.

Calochilus campestris - Copper Beard-orchid

I have only found one plant, so I consider it a very fortunate find. This is a robust plant, usually 300 to 500mm high, although the plant I found was only 200mm. It has a deeply channelled leaf and two green or coppery stem bracts.

Flowers are in a raceme of about 5 to 15. They are yellowish green with red-brown or purplish markings and a labellum that is shorter than the other two species. It is about 15mm long, triangular, sometimes with a short strap-like tip, and rather sparse coppery red hairs. There are dark shiny glands in both lower corners of the column, and smooth metalic blue or purplish raised linear markings at the base of the labellum.

The single plant I found was growing amongst sparse grasses over hard white clay. More information at PlantNET.

Purplish Beard-orchid

I'm sure you'd agree now, that there is nothing plain or boring about our native orchids. I am not aware if there is a specific insect which pollinates each species, or a range of small insects. I presume the 'beard' serves a purpose. As I learn more about these fascinating plants, I will share my observations and collection of information from those more experienced than I.

#30 Spring orchids

Spring is warming up and ground orchids are becoming more scarce in the Hunter Valley, but I've observed many from the Caladenia group in varying shades of blue, pink and white. Caladenias are dainty terrestrial orchids that are a joy to see bobbing in the breeze, but they are often not easy to identify. I am devoting this blog entry to describing species in the hope of making recognition easier for others.

Cyanicula caerulea has a single bright blue flower about 25mm across. The labellum (lip or tongue) has dark blue bars and two rows of yellowish calli.

Caladenias have recently been regrouped with some species being split into several groups. I am an orchid novice and I'm not going to attempt, at this stage, to unravel the mysteries of taxonomy, but will just accept what the experts profess.

Formerly known as "Ladies Fingers", Caladenias are now referred to as "Finger Orchids" (another example of "political correctness" gone mad). The "fingers" are the lateral sepals and petals resembling a hand of four spread fingers.

Cyanicula caerulea, formerly Caladenia caerulea, is one of the more easily-identified Finger Orchids and is often one of the first to appear in spring. I found it in massed displays in disturbed rocky soil in Werakata National Park near Cessnock in the lower Hunter Valley in late winter and early spring.

It has a single bright green basal leaf to about 70mm long by 4mm wide which tends to lie flat on the ground. Cyanicula caerulea, commonly called Blue Caladenia, bears a solitary flower on a dark scape (stem) from about 50mm to 130mm high. The flower is sky blue to purplish, and covered in minute dark blue to purple glands (hairs) on the outside.

The labellum has a white or yellow tip and is marked with dark bands. There are two rows of stalked yellow-headed calli.

The only other blue Caladenia in eastern Australia is Bluebeard Orchid or Blue Fairies (Pheladenia deformis, formerly Caladenia deformis) which has 4 to 6 irregular crowded rows of stalked calli densly covering the labellum which distinguishes it from Cyanicula caerulea. I have not seen Pheladenia deformis in the Hunter Valley and I am not aware if it is found here.

Cyanicula caerulea is also found in Victoria, ACT and Queensland and it flowers between July and September.

Notice there is no green on the column at all. This photo of Cyanicula caerulea (Blue Caladenia) shows the vertical burgundy pattern on the interior of the column and purple colouration on the underside of the labellum.

Petalochilus carneus, formerly Caladenia carnea, and commonly called Pink Fingers, is a more variable species. The colour variation ranging from pale to dark pink through to white and white tinged with pink is well illustrated by Denis Wilson on his Nature of Robertson blog. As yet, I have only observed dark and light pink specimens.

The identifying feature of Petalochilus carneus in all its shades is the dark pink horizontal banding of the upper surface of the labellum and the inner surface of the column. The exterior of the column is green. The labellum has two rows of yellow calli and a yellow tip.

Petalochilus carneus has one erect dark green leaf to 150mm long by 4mm wide, and a thin green scape to 250mm high. Plants can bear one or two flowers. This species is wide-spread and found in NSW, Qld, ACT, Vic, Tas and SA, and it flowers between August and October.

The dark pink or red markings on the labellum and column are a feature of Petalochilus carneus. Notice the green exterior of the column and the yellow tip of the labellum.

A picture of a pale pink Petalochilus carneus (Pink Fingers) with two flowers. Note that the dark pink banding can be seen through the green of the column and the white of the labellum.


The most noticable difference in these next two white Caladenias to the novice orchid observer is the colour of the column.

The column of Petalochilus pictus (left) has a green exterior and red interior, while Petalochilus catenatus (right) has a column that is green inside and out.

Petalochilus catenatus, (formerly Caladenia catenata and Caladenia alba), is commonly called White Fingers or White Caladenia. It generally flowers from June to October and is found in NSW, Qld, Vic and SA.

It has one dark green erect linear leaf up to 120mm long by 4mm wide. The green hairy scape can be up to 300mm tall holding one or two white, or occasionally pink-flushed, flowers. There are two rows of stalked club-headed yellowish calli on the white, yellow-tipped labellum.

Green column of Petalochilus catenatus

Petalochilus pictus (formerly Caladenia picta) is also referred to as White Fingers or White Caladenia. It can flower anytime between late May and October, and although predominantly white, it can also be tinged with pink.

The red of the column interior is most commonly solid, but can occasionally be split in to two sections (but does not appear in several bands).

A pink-tinged Petalochilus pictus.

My Orchid biology blog entry briefly and simply describes orchid parts and their functions.

For an easy-to-understand description of orchid pollination, I suggest reading How orchids are pollinated by Denis Wilson of Nature of Robertson. Here are a couple of my native ground orchid pictures relating to pollination.....

This fly has probably entered the labellum gap of Petalochilus catenatus seeking the nectar often found on the large basal glands. The insect can turn around as the labellum is hinged and mobile, and in its efforts to escape it can be noticed the thorax is touching the pollinia, so the next time the insect attends another flower, pollination should occur. As the stigma is situated immediately below the pollinia sac, the insect, when turning, tends to scatter the pollinia on to the column and stigma.

The pollinia have been dislodged from the top of the column in this Petalochilus carneus, and on being subject to the air, has become mealy (dry) and dropped on to the base of the labellum giving the illusion of a second set of pollinia. This procedure occurs in the genus Thelymitra (Sun Orchids) quite frequently.

My thanks to members of Australasian Native Orchid Society who helped me distinguish between Petalochilus catenatus and Petalochilus pictus as well as clarifying some aspects of pollination. I hope this brief description, together with my photos and links, will assist other novice orchid admirers identify Caladenias that they observe.

These delicate and pretty little native ground orchids are worth seeking, and I am always delighted to find them popping up in grassy open forest and amongst roadside vegetation.

#27 Winter orchids

Before the official end of winter I'd like to show off some of the Hunter Valley's delicate and pretty Greenhood orchids. At a casual glance, ground orchids often go unnoticed amongst grasses and leaf litter, but they are well worth searching out.

The twisted labellum of the Blunt Greenhood

Last week I posted a brief outline of the biology of greenhoods, along with some pictures of the delightful Nodding Greenhood, Pterostylis nutans. I've found another four species in the mid and lower Hunter.

Blunt Greenhood, Pterostylis curta, is a charming flower with a twisted labellum (tongue), somewhat resembling a cheeky cartoon character. This twisted labellum is a distinctive identifying feature. A single stem up to 30cm tall emerges from a basal rosette of 3 to 6 dark green ovate stalked leaves, and bears a single flower. The flower is surprising large, up to 3.5cm height.

The flowering season of Pt. curta is from August to October, and it has been recorded in all eastern states of Australia, as well as South Australia. It can form extensive colonies, and I have seen it growing in moss over rock, moist sheltered areas, grassy woodland and leaf litter.

My Hunter Valley sightings in August of 2007 include Werakata National Park, Watagans National Park, Broke/Wollembi and Hunter Region Botanic Gardens. More information on Pterostylis curta is available at PlantNET.

A rear view of Pterostylis curta, Blunt Greenhood

Trim Greenhood, Taurantha concinna, which has recently had a name change from Pterostylis concinna, is another greenhood with a distinctive labellum, making identification a little easier. The apex of the redddish-brown labellum is notched, forming a 'fork'.

The plant is variable in height, depending on conditions, and I have seen it up to about 20cm high. It has long erect lateral sepals. Whilst the flower is predominently green and white, there are brown tints to the lateral (side) sepals and sinus (V-shape formed at the front of the flower by the lateral sepals). More information on Taurantha concinna at PlantNET.

I have observed Taurantha concinna, Trim Greenhood, growing in leaf litter and grassy open woodland at the Hunter Regional Botanic Gardens at Heatherbrae (May, Jun), and Werakata National Park near Cessnock (Jul, Aug).

The distinctive forked labellum of the Trim Greenhood

Long erect lateral sepals of the Trim Greenhood, in this specimen, sweeping inwards to touch.

Maroonhood, Pterostylis pedunculata, diverts from the usual green to display a dark reddish-brown flower. It has a solitary narrow flower atop a stalk up to about 25cm high. The tip of the labellum is just visible through the deep 'V' formed at the front of the flower by the lateral sepals. Lateral sepals spread upwards or backwards into long linear points.

I have seen Maroonhoods growing in dense colonies at Hunter Region Botanic Gardens at Heatherbrae in the Lower Hunter Valley in a shaded moist position amongst leaf litter in August 2007. More information on Pterostylis pedunculata at PlantNET.

A Maroonhood adorned with spider web. Notice the pointed labellum is just visible

Side and rear view of Pterostylis pedunculata

Rosette of dark-green ovate stalked leaves of Maroonhoods

A colony of Pterostylis pedunculata, Maroonhoods

Tall Greenhood, Bunochilus longifolius, was formerly known as Pterostylis longifolia. It has a long scape (or stem) up to 40cm high bearing lanceolate stem-clasping leaves between 3 and 8 cm in length. At some time in its life, this plant also has a ground-hugging rosette of leaves (although I have not seen this on the plants I found).

Several flowers on the single stem open in succession from the bottom to the top of the plant. Flowers are small (12mm high by 7mm wide) and are translucent green with darker green markings. Lateral sepals are narrow and point downwards exposing an extremely touch-sensitive brown and yellow labellum. More information on Bunochilus longifolius (synonym Pterostylis longifolia) at PlantNET.

Left, the irritable labellum of the Tall Greenhood has been triggered by disturbance to flip back against the column. Right, the labellum of another Tall Greenhood plant has reset itself awaiting an insect pollinator.

Tall Greenhoods that I found flowering in grassy open forest at Hunter Region Botanic Gardens in August 2007 were not growing in dense colonies, but in sparse groupings of 2 to 6 plants.

A Tall Greenhood plant showing leaves, fertilised ovaries developed into seed pods (the brown and green swollen growths), with the top-most flower still active.

And I'll finish my list of winter orchids with some Nodding Greenhoods, Pterostylis nutans, that I featured last week. It was such a delightful group that I couldn't resist photographing them.

#26 Greenhoods get the nod

The colour green is a rarity amongst flowers, which makes greenhoods rather special. But not only are these charming little native orchids green, they have an odd, almost comical 'alien' appearance, along with fascinating lives hidden amongst grasses and leaf litter.

Nodding Greenhood, Pterostylis nutans. Notice the pollen packages visible through the translucent hood - resembling frosted glass with green veins.

Late winter has been productive for my orchid hunting in the Hunter Valley, but rather than post several of my recent finds, I'm going to share some of the details of these remarkable natives and their secret lives, along with my images of the cute Nodding Greenhood, Pterostylis nutans.

My previous orchid biology entry gives a general and simple outline of orchid structure, but greenhoods defy the 'normal' petal and sepal structure (if indeed anything amongst orchids is 'normal' or constant).

Greenhood flower structure

Orchid flowers have three sepals and three petals, although at a casual glance, greenhoods don't appear to have this configuration.

Height is variable amongst Nodding Greenhoods. I have visited the colony below on Mount Royal Road east of Singleton over a couple of seasons, and found the plants were all from 4 to 6 cm high. They were growing in moss and lichen over rock. Nodding Greenhoods I've seen in the Lower Hunter growing amongst grasses in sandy soil have been much taller - up to 18cm. [I am presuming the yellow mass in the background is a slime mould]

As their common name suggests, greenhoods have a hood-shaped flower. The two lateral (side) petals and the dorsal (back) sepal have united to form a predominantly green, hood-like structure which protects the reproductive organs.

The two lateral sepals are fused together at the base to form the front of the flower, and protrude to form 'points' or 'ears'. These points generally extend above or to the side of the 'hood'. The third petal is the labellum (or tongue) which is hidden inside the hood.

The ovary of this successfully fertilised greenhood has swollen as seed develops.

In orchids, the male and female reproductive organs are highly modified and fused together, unlike most other plant families where the sex organs are separate.

The remarkable sex lives of Greenhoods

Generally, but not always, greenhood leaves take the form of a rosette of ovate ground-hugging green leaves. All greenhoods are deciduous. After seeds have been released, the above ground parts of the plant die and the plant exists as an underground tuber.

The the seed capsule dries and splits vertically to expose the dust-like seed to the breeze for dispersal. Notice at this stage, the stem has stiffened but is not yet dead - it holds the seed capsule erect in the breeze.

Pollinia (packages of pollen grains) are attached to the tip of the anther (male reproductive organ). The stigma (female reproductive organ) is located just below the anther, and receives the packet of pollen from a visiting insect, which is then transferred to the ovary where fertilisation occurs.

Greenhood flowers are usually pollinated by gnats, and sometimes mosquitos. I didn't know what gnats were, so I checked them out: gnats are common names for a large number of small, non-biting fly or mosquito-like insects in the order Diptera of the genus Mycomya. These tiny flies do not feed. They only live long enough to mate, lay eggs, and die. Eggs are laid in masses in the water or on aquatic vegetation, and larvae feed on living and dead plant matter.

Male gnats are enticed to greenhood flowers by a scent which imitates pheromones (chemical substances) emitted by females of particular gnat species.

The labellum is extremely sensitive to touch, and when triggered by a visiting insect, flips inwards towards the column, temporarily trapping the insect. A pollen package is either collected or received as the insect struggles to escape.

The greenhood flower does not offer nectar to the insect as a reward. This is sexual deception at its best. So the poor young gnat that only has a fleeting life in which to find and fertilise a mate, is duped by this clever little plant.

From a front-on angle, the Nodding Greenhood, Pterostylis nutans, has a sharp down-turned 'beak' and lateral sepals that form points facing the ground.

Cross pollination between different species is largely prevented by using different pollinators, or by placing the pollinium on a different part of the pollinator's body.

Survival strategies of the greenhood

This group includes some of the most drought tolerant orchids in Australia. Survival strategies include the large tuberoids which store moisture; the overlapping rosette of leaves which trap moisture and direct it to the root zone; and the tendency to grow in sites of plant litter accumulation and near rocks where run-off is concentrated.

A rosette of leaves of the Nodding Greenhood

I understand that the fleshy tubers are replaced annually. Dense colonies can also be formed by asexual (vegetative) reproduction, therefore allowing plants to produce offspring without sex.

Asexual reproduction can be made at any time, even before the plant is mature enough to produce seed via sexual reproduction in which insects or other external agents play a part. Vegetative offspring are 'clones' or carbon copies of the parent. The advantage with asexual reproduction is not having to rely on chance, however, the resulting limited genetic variation could be a disadvantage in a longterm evolutionary sense.

Some greenhood species flower more profusely after fire, but if fire destroys plants before seed is set, some species will be disadvantaged.

A colony of Pterostylis nutans, Nodding Greenhoods, amongst leaf litter in open forest in the Watagans National Park.

A taxonomic review of the greenhoods has split Pterostylis into several new genera, but the Nodding Greenhood has a distinctive appearance that is easily recognised. When next you see these charming hooded ground orchids or their many cousins, perhaps you will recall their kinky sex lives or their specialised survival characteristics. They might be small, but there is nothing 'ordinary' about greenhoods.

Greenhood Links

Michorrizal fungal association of greenhoods

Denis Wilson's greenhood observations

Greenhood key - PlantNET

Greenhood biology