Christmas Bells

Christmas Bells
Christmas Bells - Blandfordia nobilis

Wednesday, October 28, 2009

Yet another Donkey Orchid

At the risk of boring everyone silly, here is a new Donkey Orchid, which I found for the first time, yesterday. It was on the road from Mittagong (Welby, actually) to Wombeyan Caves.

The particular locality was very sandy soil, with poor, low "Sandstone Heath" shrubbery around. There were lots of the lovely Purple Native Iris, (Patersonia) there.

Anyway, this Orchid looked at first glance, like Diuris pardina, which I saw at Goulburn in September. But these are flowering five weeks later.

I took a bunch of photos, to "compare and contrast", later. Sure enough this one is a different species.

I have concluded that this species is Diuris semilunulata.
I can even see a "half-moon" in the dorsal sepal of the flower (the large bit above the "labellum" and "column"). The flaps on either side of the labellum are technically, part of the labellum, and are referred to as the "side lobes" of the labellum. These are wide, and nicely coloured. The "mid lobe" of the labellum (the main part) is deeply folded, and is clearly "wedge-shaped".
One of the features of this flower is how the petals (the "Donkey ears") are reflexed back - to an almost horizontal position. The front face of the petal is golden yellow, but the reverse side of the petal is heavily spotted brownish red. It is less dark than D. pardina. All together it is a brighter red coloured flower than that plant (except for the bits which are yellow). From face on, the "lateral sepals" (the "double tails") are not visible at all - because they are so heavily reflexed back underneath the flower. They are there, as I will show you.
Here is an overhead view of the flower
It shows the "ears" and the "half moon-shaped" dorsal sepal
and Labellum.
The side lobes of the Labellum are clearly visible,
protruding either side of the mid lobe of the labellum,.
Here is a low angle view of the Flower.
You can now see the "lateral sepals" (the "double tails")
which were hidden from view before.
Contrast these with the long straight lateral sepals of the mauve Diuris
which I showed last week.
From one extreme to another.
Here is a labelled image,
to try and help with the terminology of these flowers.
This is a side-on view of this flower.
One of the petals is reflexed back so far it is horizontal.
The lateral sepals are so strongly recurved
that they actually swirl down and start to rise back up,
above the main stem (passing above the green ovary)
The petals and sepals of this flower are much more strongly reflexed
than the closely related D. pardina which I showed several weeks ago.
I would remind you that it is also much redder than that species.

Here is the full set of local Diuris species which I have seen (so far).
From the left, they are D. chryseopsis, D. aurea, D. suphurea, D. pardina,
D. punctata and today's D. semilunulata.
Click to enlarge image.
It is a larger file than normal.
To paraphrase the old political aphorism
the more they change, the more they stay the same.
Clearly quite different, but definitely all "Diuris".


Tyto Tony said...

Good of you, Denis, to do the donkey work for the rest of us!

Denis Wilson said...

Thanks Tony
It needed somebody to say it.