Tiny details of difference reveal the hybrid origins. (Well, maybe not)

I referred yesterday to the "hybrid" forms of the Spotted Sun Orchid, Thelymitra ixioides. In this case the form is known as Thelymitra x irregularis.

EDIT: My friend Colin Rowan has persuaded me that these plants are in fact colour variants of Thelymitra ixioides, NOT hybrids. The "true hybrid form" is shown from last year, at the end of this post. It has the yellow "brushes", not just the yellow pappilose tips to the column. Colin says that is the only true hybrid form in this set.

Tonight I will show a few examples of the same group of plants which were growing in a tight cluster, around two adjacent trees, within 30 metres of eachother.

As a base-line point of reference, I will start with one "standard form" of Thelymitra ixioides

column details of Thelymitra ixioides - Nowra, 28/8/2011

 Here is the other reputed parent of the hybrid forms illustrate today.

Thelymitra carnea has the pink colour and 

the yellow top of the column - the "post-anther lobe".

Thelymitra carnea - the Pink Sun Orchid.

Here is the botanical illustration of what I have photographed 
of Thelymitra ixioides (first image above).

PlantNET botanical illustration - note the "papillose-toothed tips"

To make matters worse, here is the botanical description from PlantNET.

"Column to 5 mm long, erect, bluish. 

Midlobe with a dense rows of long, variable, colourful calli; 

accessory lobes columnar, erect with papillose-toothed tips. 

Lateral arms obliquely erect, 

with terminal tufts of white, pink or mauve hairs." 

"Papillose" literally refers to the "nipple-shaped" tips at the back of the column.
Don't blame me - its the botanists who invent and use these terms.

See the illustration for "pappilate" - middle level, 3rd from left.

Anyway, having established what we are looking at, lets move on.

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This is yesterday's plant, which is closest to the lilac coloured form 

which is illustrated in David Jones's book (P. 256)

as "Thelymitra x irregularis".

The ring of pappilose nodes in the back of the column

are yellow in this one.

They are black in the "species" form.

Colin points out Jones shows a plant with yellow brushes

not white as in my plant.
See the two last images in this post for the true hybrid form

Column details for Thelymitra ixioides.

This is one is the clearest pink of the hybrid plants I photographed today. 

This one has a red collar 

underneath the golden pappilose nodes.

One of the pink forms of "Thelymitra ixioides".

And my personal favourite image of these column details.

This flower was in-between pink and lilac in colouration.

I like the way the 'arms" turn away from eachother.

Thelymitra ixioides

This next specimen looks as if something has interfered with the pollinia.

From the looks of it, there is a pollen sac stuck on top of the 

 "accessory lobe" the yellow protruding structure

on my left-hand side of this image.

Thelymitra ixioides

***********************

Last year, at Penrose cemetery I even photographed a pink hybrid form

with golden coloured lateral arms 
(instead of the normal white or bluish fluffy "brushes").
So, although it is outside today's "cluster" of hybrid plants,
it is worthwhile showing, for the full contrast it offers.

Pink hybrid Thel. x irregularis - note the golden column arms.

I have never photographed such a flower before.
 This image is a view of the column of the same flower,
photographed from the side view. 

It shows both the golden "pappilae" at the back of the column
and, more significantly, the yellow "arms".
All the other plants photographed have white column arms.
Colin agrees this is the true hybrid form

Thel. x irregularis note the yellow "brushes".

This is an even more extreme hybrid form than any I have seen this year. Interestingly, Colin and Mischa's images of this species, also taken in 2010, might well be of the same plant as I photographed last year on the ANOS Southern Highlands excursion.