Australian Orchids: The How, Where, When & Why

It’s been a little while in coming, but here is the second of a three part educational video about Australian Orchids.

Orchids are special.

They are unique but even more they are important. Orchids are the barometer to the health of the ecosystem.

So, watch and enjoy the video …

To watch the first video click here.

What makes an Orchid and Orchid?

Orchid flowers are extremely variable in appearance, ranging from mimicking spiders, flying ducks, helmets, ants, etc. This variety also can cause some confusion. People have mistaken a different type of flower for an orchid and vis a versa.

This raises the question of what makes an orchid an orchid? With so much variety, how can they possibly belong to the same family?

Using orchids found in the Adelaide Hills, the following video shows three key features that helps identify a flower as an orchid. These three features are found in all orchids worldwide.

So watch and enjoy …

Orchid Hunter Visits Kuipto

The following video is by Orchid Hunter, Julian Pitcher.  Julian is concerned about the conservation of orchids and is also keen to teach others about Australia’s unique orchids.  At the time of the visit, Julian was resident in Victoria; now he resides in Queensland.  Enjoy an interstate visitor’s view of our beautiful orchids.

Moving Labellums

The following article titled Moving Lablellums written by Helen Lawrence is reproduced from the NOSSA Journal Volume 36 (1) February 2012

Labellums are fascinating. Well I think they are fascinating, especially the ones that move.

Bunochilus viriosus labellum down
Bunochilus viriosus with the labellum down

Why do these labellum move? You may have observed that the orchids which have labellums often have “hoods” and inside these “hoods” are the pollen. It is quite simple, the pollinator lands on the labellum, triggers it and is held captive by the labellum. As it struggles to free itself it pollinates the orchid. Clever, isn’t it?

Bunochilus viriosus labellum up
Bunochilus viriosus with the labellum up

So that these labellums can capture the insect they need to be sensitive. Consequently they can easily be “set off.” This can happen with of a gust of wind, or if the plant is in a pot, the labellum may trigger if the plant is moved/knocked.

It is easy to see these labellums as they move up into their “triggered position.” They move reasonably quickly, so the insect does not have time to respond.

However, how does the labellum return to its “normal” position? Does it slowly return to the position, or does it happen in a sudden movement in the same manner as when it is triggered?

One day when I was travelling in the car with a Pterostylis curta (Blunt Greenhood), I observed something very interesting. When I looked at the flower, the labellum was up, but then when I looked at it a minute or two later, the labellum was down. The labellum had to move quickly. However was it the bumps in the road which caused it to move? I had to find out.

I devised an experiment to satisfy my curiosity, and find out what these fascinating labellums actually do.

First I had to find an orchid with a labellum that could be triggered. I ended up using an Oligochaetochhilus bisetus (Two-bristle Greenhood).

Oligochaetochilus arenicola
Oligochaetochilus arenicola

Second I had found a good camera that could take high definition video. I placed it on a “tripod” (a pile of books).

So I had set up my apparatus, set the camera rolling, triggered the labellum, and left the room.

So what happened?

For the first six minutes after I had triggered the flowers nothing happened. There was no movement that I could see.

In the next five minutes, the labellums of the two flowers slowly moved downwards until they were half way down.

After twelve minutes of the flower being triggered, the labellum returned rapidly to its original position. This final stage of the labellum moving lasted for less than five seconds, and appeared to move at the same speed as when it was triggered.

So it looks like the labellum returns to it normal position first moving slowly and then in a rapid final movement which returns the labellum to its original position.

Urochilus sanguineus
Urochilus sanguineus

If I thought it would be that simple, I was mistaken.

As I briefly looked through the fifty minute video I took, I came upon something that made no sense to me.

A minute after the labellum had returned to its resting position, one of the labellums suddenly returned to its “triggered” position. What’s more, there was nothing in the room to trigger the labellum: no wind, no insects, and no people. So what triggered the flower?

I do not know. Six minutes after the labellum was triggered it returned to its original position, and then two minutes later the other flower’s labellum moved into the triggered position. The first flower was triggered again for no apparent reason at all, four minutes after the second flower was triggered and still remained up.

Once the labellums returned to their original position, there was no more movement.

Maybe triggering the labellum causes a chain reaction. Maybe the labellums periodically “trigger themselves.” Well, I can’t give you any answers, all I can tell you is that it looks like this is an example of how we barely know anything about these wild gems. They are beautiful but bizarre and of course fascinating!

After 7 minutes, just before the labellum moved
After 7 minutes, just before the labellum moved

After 12 minutes, labellum about to fall
After 12 minutes, labellum about to fall

After 13 minutes, labellum in original position
After 13 minutes, labellum in original position

 

 

 

 

 

 

 

 

 

 

 

As a 50 minute video is a bit long to watch, Helen has produced a four minute video, so watch and enjoy the music!

Greenhood Pollination Strategy

Since orchids, and Australian orchids in particular, first came to the attention of the western world in the 1800s researchers have been fascinated by the so many different aspects of the orchid’s morphology and life cycle. One area of interest has been that of how orchids are pollinated. The mechanism of pollination has not always been clear as the orchids seem to use different and complex methods.  From time to time various papers have been published of observations by researchers.

One such paper was published in the Annals of Botany 113: 629 – 641, 2014 titled ‘Caught in the act: pollination of sexually deceptive trap-flowers by fungus gnats in Pterostylis (Orchidaceae)’ by R D Phillips, D Scaccabarozzi, B A Retter, C Hayes, G Brown, K W Dixon and R Peakall.

The ‘question and answer’ style of the paper helps with ease of reading and is worthwhile perusing, even for the lay person. The accompanying VIDEO is also of interest.

The essence of the paper was to establish whether sexual deception was used to facilitate pollination.  The species researched was Pterostylis sanguinea (syn. Urochilus sanguineus) and the researchers confirmed that this did happen.  Their research showed that the attraction for the insect came only from the labellum which exuded an alluring chemical.  P. sanguinea has a mobile hinged labellum which is a feature of other sexually deceptive orchids such Paracaleana, Caleana, Arachnorchis.

Urochilus sanguineus RWL
Pterostylis sanguinea syn. Urochilus sanguineus with the untriggered labellum

Urochilus sanguineus RWL(1)
Pterostylis sanginea syn. Urochilus sangineus with a side view of the labellum

 

Orchid Season

South Australia has some very interesting and unique orchids but it is not always possible see them  either because one cannot get out to see them or the season has been poor with inadequate rain at the right time.  So, one of NOSSA’s member has produced a video.  It starts in autumn and goes through to summer.

So sit back and enjoy ……

Orchid Etiquette – Tread Carefully

An important first lesson to learn when out orchid hunting is to watch where you put your feet.  In this video the Orchid Hunter explains the how and why for watching where you step.

Related Article

Protect Our Orchids – Stay On the Path

Orchid Walks at Mt Lofty Botanic Gardens

For the last couple of years, NOSSA has been conducting spring tours at the Mt Lofty Botanic Gardens, South Australia, showcasing our beautiful native orchids to visitors far and wide.  They have come from not only Adelaide but from interstate as well as overseas from such countries as America, Germany, England and many others.  If you are planning to be in Adelaide during spring, then consider joining one of our walks, but for those who cannot attend here is a video for you.  So watch and enjoy …….