Monday, 29 October 2007

#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.

8 comments:

Esperance Blog said...

Hi Gaye, another interesting blog. I think there are more people interested in the orchid family than any other, so your records in this area I am sure will attract many enthusiastic readers.

Regards
Jack

Denis Wilson said...

Hi Gaye.

The Microtis down here in the Southern Highlands have just started. I got my first photos (this year) this weekend.
I have only seen one Brown Beaks (last year), Poor specimen (finished flowering), so I have no photos. Your photos are very good.

Do you have Diuris up there? Ours are flowering madly now - mostly the yellow "Tiger" Orchids(D. suphurea). They occur in patches. here and there, on the sandstone. They seem to like roadsides, and under power line easements.

Our Tongue Orchids are budding up now. Then it will be Hyacinth Orchids, and Potato Orchids, through till Christmas.

Keep hunting.

Denis

David said...

Fantastic and informatic article Gaye! I've never seen brown beaks growing in the wild, I'm most jealous!

Denis Wilson said...

Hi Gaye

I'll bet you were surprised when you put that list together, at how many you have covered. Well done.

Keep up the good work on Orchids, (and everything else).

Denis

Gaye from the Hunter said...

Thank you Jack, and I am sure you are right about Orchids being a popular nature interest. The more I observe, the more I too am interested. And the more I learn, the more questions I have.

Regards
Gaye

Gaye from the Hunter said...

hi Denis,

I will be very interested to see what species of Microtis you find in your area.

A fellow photographer of wild native orchids has suggested that my Onion Orchid could possibly be M. parviflora instead to the M. unifolia that I have identified it as. This is something well worth following up, which I will do. I really appreciate input in the area of questioning. It promotes further investigation and more detailed study, which is very productive and educational.

As your local Microtis species begin to bloom, perhaps you could make a comparison between them and my specimen here, please.

My photographs are not clear enough to detect the minute differences between species, and I will shortly revisit sites in an attempt to get better images that can stand the severe cropping necessary to bring the tiny 3mm individual flowers up close.

Yes, Diruis species are flowering here - also mostly D. sulphurea. They make a spectacular show. I am extremely envious of your D. punctata find, and although its season should be finished here, I am always hopeful of a sighting.

Regards
Gaye

Gaye from the Hunter said...

hi David,

thank you. My Brown Beaks find was right at the end of the flowering season, so I will be revisiting the site earlier next season in an attempt to find fresh specimens to examine and photograph. They were well hidden amongst the grass and I walked right by them without seeing them on my first visit. It takes a keen eye and much persistence to spot some of these hidden treasures, but of course, sometimes there's a good dose of luck involved also :)

Regards
Gaye

Gaye from the Hunter said...

Note:

After following up a suggestion from a reader of my blog that my Onion Orchid could well be Microtis parviflora instead of M. unifolia, this has been confirmed by an experienced orchid enthusiast from ANOS, and hence I have made alterations to my blog entry.

Thank you to those who took the trouble to question, offer suggestions and to answer requests.

Gaye