2017 July Winning Picture

July Winning Photograph

Corybas demenicus

July is Helmet Orchid Season; and the theme for the July Picture Competition.

In Australia, the genus Corybas in the broad sense (sensu lato) has four segregate genera; three on the Australian mainland (Corybas, Corysanthes & Anzybas) and one (Nematoceras) on Macquarie Island. All three mainland segregate genera were represented this month. Robert Lawrence’s, Anzybas unguiculatus; Margaret Lee, Corybas aconitiflorus with Jane Higgs, Lorraine Badger and John Fennell all entering Corysanthes diemenica. Lorraine also entered Corysanthes despectans; and John an image of Corysanthes incurva. The clear winner was Jane Higgs’ Corysanthes diemenica (synonym Corybas diemenicus).

The flower of Corybas sensu lato is characterised by a large dominant dorsal sepal and an equally dominant labellum. The other features associated with an orchid are not so obvious. The column is short and not visible. Even the ovary is barely visible whilst the other petals and sepals are but short thin filaments near the ovary. The base of the labellum wraps around to form a tube which hides the column; and the upper portion of the labellum folds back on itself and flares out. With this structure, two new features are introduced, the boss in the centre of the labellum and the auricles, two earlike openings formed from folding at the base of the labellum. Two growth features that are different from many other orchids are that the bud and leaf grow concurrently and once pollination has occurred the stem elongates so that the ovary can be raised up to 20 to 30 cms, thus allowing for seed dispersal.

Jane’s picture clearly shows these features as in the labelled image below.

Corybas demenicus

Thank you to Greg Steenbeeke for reviewing this article.

Reference

Backhouse, G, et al (2016) Bush Gems: A Guide to the Wild Orchids of Victoria Electronic version

Bates, R. J., ed. (2011). South Australian Native Orchids. Electronic version, 2011. NOSSA

Jones, D. L., A Complete Guide to Native Orchids of Australia Including the Island Territories. Reed New Holland

Jones, D. L.; Hopely, T; Duffy, S. M.; Richards, K. J.; Clements, M. A and Zhang X, Australian Orchid Genera an information and identification system. Electronic version, 2006, CSIRO

Rules of entry:

The subject matter must have something to do with Australian orchids.  Any format is acceptable including Photo shopped images, artwork, etc

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Orchid Basics – Labellums and Columns

Orchids are unique in the floral world. Two distinctive characteristics that set orchids apart from other plants are the labellum and the column.

The labellum is a modified petal.  It is extremely varied in appearance; “often lobed, spurred, adorned with glands, appendages of calli (callus, a hardened swelling or thickening of the skin), sometimes mobile and highly irritable and often brightly coloured”. * The labellum is important for pollination.

The column (as described by Bates and Weber) “is a distinctive feature of all orchids and a unique structure in the plant kingdom. It is formed by fusion of the male parts ‘stamens’ and female organ ‘pistil’.”*

Below are examples of the various types of labellums and columns in some South Australian terrestrial orchids. Each genus has its own characteristic labellum and column.

Sun Orchid

Thelymitra – though the labellum is almost indistinguishable from the other petals and sepals, the column is quite complex.

Hyacinth Orchid

Dipodium or Hyacinth Orchid

Greenhood

Pterostylis or Greenhoods – generally a simple labellum with the column hidden well back into the hood.

Spider Orchid

Arachnorchis (syn Caladenia) can have quite varied and complex, mobile labellums

Helmet Orchid

Corybas or Helmet Orchid – the labellum dominates and the column is hidden deep inside the flower.

Donkey Orchid

Diuris or Donkey Orchid – the labellum is divided giving the appearance of more than one structure.

*Bates and Weber Orchids of South Australia 1990

 

UPSIDE UPSIDE DOWN

Leo Davis always has some interesting insights from his orchid observations.  In this article he examines the position of the tepals (petals and sepals) in particular the Moose Orchid which he saw for the first time this year.

Have a close look, next season (winter to early summer) at some of our native lilies.  Start with the jolly bulbine lily (Bulbine bulbosa), no longer a true lily incidentally, because it now resides in family Aspodelaceae, along with the grass trees. You will find three yellow petals at 12, 4 and 8 o’clock and closely behind them three almost identical sepals at 2, 6 and 10 o’clock, so at first sight you see six apparently identical tepals (sepals and petals).  Move on to the rush fringe-lily (Thysanotus juncifolius), as described in Ann Prescott’s ‘It’s Blue With Five Petals’.  Clive Chesson is more up to date and tells me it is now T. racemoides.  Again it is no longer a true lily, now sitting in family Asparagaceae.  Here the tepals are noticeably different.  Three wide densely fringe edged petals will be found, if you view the flower face on, at 12, 4 and 8 o’clock.  The narrow non fringed sepals sit close behind at 2, 6 and 10 o’clock.  These are just a generalisations because if the flower turns only about 60o a sepal will be at the top.

Most orchids, while close relatives of the true lilies and the one time lilies, do not show these arrangements.  Let’s start with some that do.

In the large duck orchid (Caleana major) the petal at 12 o’clock, the dorsal petal, is modified, as in most, but as usual, not all, orchids, to become a labellum.  In this charmer the labellum takes the form of a duck’s head.  Its function is to snap down trapping a pollinator insect in the cup shape column below it, forcing it into contact with the sticky off white stigma and/or the yellow pollinia below it.  Look closely and you will find the other two narrow petals drooping at around 4 and 8 o’clock.  Two folded, twisted sepals can be clearly seen at around 1 and 11 o’clock.  The third sepal, at 6 o’clock, is tucked in behind the cup shaped column.  Note that, as with lilies, the top tepal is a petal.

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Caleana major, Knott Hill NFR Photographer: Leo Davis

The leek orchids (genus Prasophyllum) follow this pattern and also have their labellum at around 12 o’clock.  These orchid groups, which are up the right way, are said to be ‘not upside down’, using the technical term ‘non resupinate’.

Most orchids are ‘upside down’ and are called resupinate.  The whole flower rotates 180o, clockwise or anti I don’t know, at the embryonic stage.  But let’s start with somewhat of an exception with the sun orchids (genus Thelymitra) which do not have a petal modified as a labellum.  But they are indeed upside down.

Have a close look at the Thelymitra benthamiana flower.  Note that the three petals, at roughly 2, 6 and 10 o’clock, are in front of the three slightly larger but very similar sepals, at 12, 4 and 8 o’clock.

Note that the top tepal is a sepal.  The flower is upside down, that is resupinate.  In most orchids the petal at 6 o’clock would be modified to be a labellum.

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Thelymitra benthamiana, Scott Creek CP; Photographer: Leo Davis

The Arachnorchis (possibly Caladenia to you) stricta, from Sherlock, out in the mallee, is more typical of terrestrial orchids in SA.  It is upside down, that is resupinate, and has a petal modified to be a labellum.

The bottom petal has become a wide labellum, with fine edge combs and parallel rows of rich plum coloured calli covering its centre.  Out at roughly 3 o’clock is a narrow petal, the other invisible on the other side.  At the top, pressed tightly against the column, a sepal arches forward.  Two larger sepals extend down at around 5 and 7 o’clock.

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Arachnorchis stricta, Sherlock; Photographer: Leo Davis

When I saw my first, my only, moose orchid, this season, I was in such a state of excitement that it looked to me to be up the right way, that is to say upside down.

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Cryptostylis subulata, Stipiturus CP; Photographer: Leo Davis

Have a look.  Two narrow short roughly vertical petals at about 1 and 11 o’clock.  There are two sepals at just past 3 and just before 9 o’clock. That’s OK but where is the other sepal?  Are there it is, where it should be, at midday.  But hang on, it’s behind the flower stem (peduncle) and where is the column?

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Cyrtostylis subulata with labellum lifted; Photographer: Leo Davis

Holding the labellum up with a stick I found the column, the stigma and the pollinia, underneath the labellum.  The third sepal now appears to be at 6 o’clock.  And it all became clear.  This flower was up the right way (non resupinate) but it has turned forward, on its peduncle, by about 180o, to become upside down, but not in the manner of resupinate flowers, because it is back to front.  It is an inverted non resupinate flower.  Still with me?

The Ducks – Taking A Different Perspective Part One of Two

Leo Davis is an orchid enthusiast with an eye for detail.  Everyone seems to be aware of and gets excited over the flower of the large flying duck orchid but in the article below, Leo takes a look at a more significant event – the rare fruiting of the duck in South Australia.

TAKING A DIFFERENT PERSPECTIVE 1(The Large Flying Duck Orchid)
Leo Davis

When approaching an iconic orchid like a flying duck orchid the obvious imperative is to emphasise the flying duck image. But as much fun as that can be, we can find and record some other significant aspects of this species.  Do remember to look at all orchid flowers, with or without your camera, from different directions. And don’t forget the leaves.

In the last flowering season at Knott Hill NFR (Oct-Dec 2015) I photographed a double flowered large flying duck (Caleana major) on November 14.  At the bottom of the upper left hand side flower you can see a white stigma (♀ part), sitting at the base of the bowl shaped column. The sticky surface of the stigma is ready to trap a pollinium (a sack of pollen grains), if the correct pollinator arrives, with a pollinium attached. Immediately below is a three lobed the triangular yellow pollinium packet (♂ part), as yet not taken by a pollinator.  The highly sensitive mobile duck shaped labellum, a modified petal, looms above, waiting to slam a visiting insect down onto the pollinium, so attaching it to the back of the insect.

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Caleana major (Flying Duck Orchid) – note the location of the stigma and pollinium

On December 10 I found the same plant, and one adjacent, in FRUIT. This is not often observed in South Australia and it has been suggested that the specific pollinator may be thin on the ground.  I photographed both plants but that of the more advanced plant (shown), with fully withered flowers and plump developing ovaries, interested me more, because it suggested progress towards production of viable seed.

Caleana major fruiting body

Success – Caleana major Fruiting Bodies

I went back on March 9, this year, and was delighted to find and photograph the fruit that had ripened, dried and split, so releasing the dust like seed.  I was prepared for disappointment because the fate of seed pods of many orchid species is to be eaten.  For example for the hyacinth orchid (Dipodiun roseum), across both the 2014-15 and 2015-16 flowering seasons, at Knott Hill, all plants that I found had their seed pods consumed. Kangaroos?

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Dehiscent (splitting of the seed pod to allow dispersal of the seed) Caleana major

Robert Brown established the genus Caleana based upon his description of a specimen of Caleana major (1810).  The type specimen was collected in 1803, at Bennilong Point, the site of the Opera House, so the species is extinct at that site now, of course.