Christmas Bells

Christmas Bells
Christmas Bells - Blandfordia nobilis

Monday, October 19, 2009

Petalochilus mentiens (Lesser Fingers Orchid)

On Saturday morning I went to the Tourist Road area (in Kangaloon), to check what Orchids had come into flower while I had been away, in Sydney, doing some birdwatching, with fellow Aussie Nature Bloggers, Mark Young and Chai.

Anyway, to my delight I saw a tiny pink "Finger Orchid" which I had never seen before.
When I say tiny, I mean, really tiny.
This tiny image is approximately life size.
Check your left hand little fingernail against mine to check image size.
then look at the flower again. That is how small it is.
I rang Alan Stephenson to ask his advice and he suggested that I check the ID against Petalochilus mentiens and Petalochilus pusillus. I did that, as best I could, as the reference texts, and the internet are not all up to date.
P. mentiens is recorded by David Jones in his "Complete guide..." as being found in NSW (north to Nowra), ACT, Vic and Tasmania. Jones says P. pusillus is found only in Tasmania and S.A. The main difference I could find between these descriptions is that the lateral sepals of P. pusillus are often fused (not separate "fingers"). But then I found an image by Mark Clements (CSIRO), which gives the locality of his flower as Bowral, NSW - just up the road from Kangaloon. His image is so close in colour, hairiness, and form to my plant, that, in conjunction with the distribution notes from the Jones book, I have gone with these plants as being Petalochilus mentiens.

Interestingly, my blogging colleague "JL" on the Fungi of Great Western has posted about Petalochilus pusillus, which she has found in the Grampians, just a few days ago. So these tiny Finger orchids are both following the same seasonal cycle (several weeks after Pet. fuscatus). Have a look. Her plant has the fused sepals referred to by David Jones as typical of that species.

Here is a side-on view of the first flower I found. Its dorsal sepal is very closely hooded, but the books say it is a Petalochilus, not a Stegostyla (the new name for the hooded "Caladenias").

Note how extremely hairy the plant is - on the stem and the flower.
Obviously these images are taken with my Macro lens.
Click to view full detail of flower.
Here is another plant located today - with similar features.
I subsequently found others with more erect dorsal sepals.
In fact, I found about 50 of these flowers over about 300 metres
of roadside verge. Amazing that I had never seen them before.
Then again, they are tiny little flowers.
Another view from the front, with a 10 cent coin (Aussie) for scale.
(I acknowledge that Colin of "Retired Aussies" website
uses this system of using coins for scale - it's not my idea.)
Another plant with erect dorsal sepal, seen from the rear/side.
Note the dark red stripe down the rear of the dorsal sepal,
which extends right down the ovary below the flower.
Here is a close-up view of the column of the flower (from a low angle).
This particular flower has one petal not quite fully opened.
You can see the yellow pollinia inside the apex (tip) of the column.
The labellum has strongly coloured yellow "clubs", and the tip of the labellum is also yellow, but paler, and is curved down and under.
(remember this image is taken from very low down).Here is a silhouette image of the leaf and stem.
It is of one of the flowers photographed on Saturday.
This tends to confirm the comment that the flowers only open very briefly.
This image is taken against a piece of paper,
which I was using to record detailed notes of the size of the plant.
Click to enlarge to see details.
Here is a normal view of the leaf, against my finger, and the stem.
Both are labelled, to clarify the issue.
Dimensions of the plant.
I measured two flowers, and their sizes were:
Plant A (with erect dorsal sepal)
Height of flower stem (ground to top of flower) 7o mm
Flower width (total) 8mm
Flower depth (top to base) 8.5mm
Leaf 55mm high, X 1.8mm wide (hairy).

Plant B (with hooded dorsal sepal)
Height of flower stem (ground to top of flower) 80 mm
Flower width (total) 11mm (the largest flower of this species I saw)
Flower depth (top to base) 10mm
Lateral sepals 6mm long
Dorsal Sepal 6mm long

I am pleased to note that I have found (and linked above) an image of Petalochilus mentiens published by Andrew Paget, on his Flickr Album "Wildwood Flora" photostream. That is the only (other) named image of this plant which I can find with a Google image search.


mick said...

Beautiful flowers and fantastic photos! Your macro lens brings out details that I assume are almost impossible to see with just eyes! The flowers are so tiny I think most would simply walk over them :-(

Junior Lepid said...

This is interesting, Denis and thank you for explaining the difference between P. pusillus and P. mentiens (fused sepals)

They are tiny orchids.

Denis Wilson said...

Hi Mick and JL
Yes, they are easy to miss, or walk over, hidden down amongst the grass.
I could barely believe it was a "Finger Orchid" when I found it. Flowers not much bigger than a tiny pink Sun Dew (of which we have many just coming into flower).
Thanks - both for your comments. JL thanks for the link from your post re Steg cucullata and Pet pusillus.