Yellow "Donkey Orchids" - two species

Here are two species of Diuris, the popularly named Donkey Orchids. I have another one to come - a mauve Diuris - which I will publish in the next few days.

Basically, one is spotted on top of the dorsal sepal (the hood covering the centre of the flower) and it has plain yellow "ears" (the petals). The other is more or less golden, with few markings. Its dorsal sepal is very rounded, and the labellum is very deeply pleated (folded) leaving a very prominent ridge. Both have prominent, raised petals, known as "ears" - earning them the nick-name of Donkey Orchids.

The first one is Diuris sulphurea, known as the "Tiger Orchid" or the "Hornet Orchid". My Aussie Nature Blogging colleague, Gouldiae, in Gippsland, published an images of this same species yesterday. It is a wide-spread species. These plants are very common on shallow "black soil" over sandstone of Kangaloon, along the slashed fire-break beside Tourist Road.

Here is a high shot of the full flower head.

The Petals ("Ears") are swept back.
They are plain yellow on both sides
(unlike D. pardina I showed 10 days ago).

Here it is seen from the side view.
One of the two spots on the dorsal sepal is clearly visible.
The matching "dot" is on the other side, of course.
The stalks of the petals are relatively long and dark brown
(below where the petal "ear" becomes yellow).

This view shows the column deep within the flower.
The dorsal sepal is ridged.Click to see the full detail of the flower.
The flat plate inside is the front of the "column"
The dorsal sepals are slightly crossed in this specimen.

The second plant is one I saw in the Royal National Park, last week, in a sandstone heath area, approximately 3 Km past Audley Weir and the NPWS Office there. This species is Diuris aurea - one I have never seen before.

This image shows the labellum with a prominent ridge down the middle.
The rest of the flower is relatively plain.
So it is basically a yellow flower,
but it has prominent ears, which are more or less upright,
unlike the plain yellow Diuris chryseopsis I showed 11 days ago.

Here is the full view of the flower.
The dorsal sepals (the two bits below the flower)
are green, and not crossed over.
You can see that the labellum has two callus ridges,
beyond the main folded pleat in the labellum. They are outlined in brown.

In this image, which is taken from a slightly lower angle,
you can clearly see two small wings beside the column.
They are sticking upwards like two little hands.This is a cropped image of the labellum and the column.
You can see how the dorsal sepal is rounded,
(like an old-fashioned "bonnet" style of hat).

Here is a shot of the full head of flowers.