Saturday, 2 June 2007

#20 Autumn orchids in the Hunter Valley

Australia's native orchids are not always bold and showy like their potted exotic cousins adorning home greenhouses, but they certainly surpass their frilly relatives in the quaint and curious departments. I am always excited to fine the tiny blooms of our native orchids, often in the most unexpected of settings.

#1 Chiloglottis reflexa, Autumn Bird-orchid, 29Apr07

Orchid biology and ecology is complex, but I have investigated the subject and extracted some of the basics explaining flower components, growth and reproduction habits, and environmental requirements. You'll find this brief and simple overview here.

Chiloglottis reflexa - Autumn Bird-orchid

The most distinguishing feature of this pretty little flower is the cluster of shiny black calli (lumps or nodules) adorning the labellum (lip or tongue). This flower is pollinated by means of sexual deception (pseudocopulation). The calli mimic the appearance of the flightless female Thynnine wasp, and as the male wasp flies in to mate with the insect-like lip, it collects or deposits pollin. Ingenious!

Image #1 clearly shows the two lateral (side) petals hugging the swollen top of the stem where the ovary is situated, and the two slender lateral sepals curved forward under the labellum. The dorsal (upper back) sepal stands erect protecting the column which contains the sexual organs.

#2 A close-up of the labellum of Autumn Bird-orchid

I found the Autumn Bird-orchid in sandy soil growing in semi-shade in the Lower Hunter, where there were dense colonies of leaves with very few flowers. Each plant has two green ovate leaves with wavy edges (picture #3), and a solitary 15mm flower tops a solitary stem to about 150mm. Flowering is chiefly March to May. Note: I am not positive that my identification of Chiloglottis reflexa is correct, as there is another very similar species, Chiloglottis seminuda.

#3 Leaves of Chiloglottis reflexa, Autumn Bird-orchid

I was thrilled to find the next dainty little red-throated white ground orchid growing alongside the orchids in #5 and #6 images, in sandy soil amongst leaf litter and moss.

Petalochilus pictus - White Lady Fingers

Petalochilus pictus has been recently reclassified and was formerly known as Caladenia pictus. Upon noting the red throat and upright dorsal sepal of this flower that I had formerly known from the Caladenia group, I immediately recognised it from Denis Wilson's Nature of Robertson Blog. The value of sharing nature observations and knowledge via the internet medium of blogging chimed loud and clear as I chatted away to myself, smiling broadly, amongst the bush. If the birds didn't consider me crazy, I'm sure passers-by did.

#4 Petalochilus pictus, White Lady Fingers, 28May07

This orchid has one green strap-like leaf arising from the stem base at ground level, and can flower anytime between late May and October.

Corybas aconitiflorus - Spurred Helmet-orchid

Some of the Helmet-orchids have also been reclassified, but the Spurred Helmet-orchid remains in the Corybas group.

The single heart-shaped green leaf has a reddish-purple undersurface, and the dorsal sepal is large and hooded, almost hiding the labellum from view. This odd little orchid flowers from April to June in damp protected ground litter.

#5 Corybas aconitiflorus, Spurred Helmet-orchid, 20May07

Ground orchid buds and flowers must appeal to the appetite of some creatures, because upon revisiting the site of the cluster of budding orchids in picture #6 below, all flowers had been chewed off.

Acianthus fornicatus - Large Mosquito Orchid, or Pixie Caps

Although green and inconspicuous, these 10mm flowers have their own special appeal. The broad dorsal sepal arches over the column, projecting forward to a fine point. The single stem-clasping heart-shaped leaf has a purplish undersurface, which is evident in image #6 below.

#6 Leaves and budding stems of Acianthus fornicatus

I found this orchid growing in sandy soil in a shaded position amongst leaf litter. Dense mats of leaves produced very few flowers.

#7 A close-up of Acianthus fornicatus flower

Images #1 to #7 are of terrestrial (ground) orchids, but my final autumn orchid is an epiphyte (aerial) orchid.

Bublophyllum exiguum - Autumn Bulbophyllum or Mat Orchid

Both the 5mm pseudobulbs and the deeply furrowed leaves are readily seen forming a creeping network on living trees in damp forests. The 10mm greenish to cream flowers have a protruding yellowish labellum, and the sepals are larger than the petals. Flowering period is March to May.

#8 Bulbophyllum exiguum, Mat Orchid, 17Apr07

So when you're out enjoying the outdoors, keep an eye out for these delicate little beauties of the Australian bush. Although most native orchids flower in spring, I have been very pleased to find some flowering in autumn and even winter. Have fun with your orchid spotting.


Denis Wilson said...

Hi Gaye
Great photos, interesting discussion too. I think you have done a terrific job of promoting interest in native orchids here.
I would favour Chiloglottis seminuda, based on the length of the lateral sepals. However, it is hard to tell these thing apart. The botanists use microscopic analysis. Also, the range, quoted in the books does not quite fit Ch. seminuda (Blue Mtns to Clyde Mtn).
Ch reflexa is sometimes called the Short-clubbed Wasp Orchid, referrring to its relatively short lateral sepals.

You need an expert opinion. Your photos are very good, and should give you plenty of opportunity to get a second opinion.

Round the Southern Highlands (and Kangaroo Valley) Bulbophyllum species are found growing on rocks, in shaded positions, on cliff ledges. So, the distinction between lithophytes and epiphytes is not a hard and fast distinction. In both cases they use the tree or rock as a platform, a vantage point.

Great work. I look forward to seeing more and more posts on Orchids over the winter and spring, and summer as the seasons move on.

Gaye from the Hunter said...

hi Denis, and thank you for your feedback.

The track that I walk in the rainforest of Barrington Tops NP is partly closed due to a domestic fire a few months ago, but I'm still hoping to get into the forest to do some orchid and fungi hunting over the next few months. And I'm planning to take a long (16km) walk in the spring, a track that I haven't taken before.

I imagined that Bulbophyllum species would also grow on rocks, so it's interesting that you have seen them. I'm presuming your area has considerably much more accessible natural areas to explore.

I'm looking forward to trying to record as many local orchid species as possible. And I'll work on a second opinion for the Chiloglottis species.


David Young said...

Hi Gaye,

Dennis Wilson and I were discussing orchids, and he showed me your site.
I was most impressed with the photography, especially your section on spiders.
As your site warrants further inspection, I'm off for a better look and have added you as a link from my site.

All the best


Gaye from the Hunter said...

hi David,

I'm pleased you are enjoying my nature observations and photography. And thank you for your positive feedback.

My direction has changed with my photography since my interest in the details of nature has increased. With my photography, I am now able to study my subjects in much more detail after the creature has scurried away, or after the flower has wilted. This brings great delight to me as well as an opportunity to learn about nature and the environment, and share my enthusiasm and interest with others.



Col Bower said...

Hi Gaye,
Your excellent photo of Chiloglottis reflexa is neither C. reflexa or C. seminuda - it is Chiloglottis diphylla, a common coastal species in NSW and southern Qld. north from about Nowra.

Gaye from the Hunter said...

hello Col,

thank you very much for commenting and correcting my orchid identification. I appreciate this very much.

I have found a couple of pictures of Chiloglottis diphylla on the internet, and indeed the flower is extremely similar to Chiloglottis reflexa.

Can you please explain to me how the untrained can tell the difference. I would be most interested to be able to correctly identify my local species.

Thank you kindly for your comment.