#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.