Friday, 26 October 2012

Some Carwoola orchids and a question answered

The Diuris semilunulata towards the top of the block are now blooming well.
I marked a spot where some Microtis sp leaves were seen.  Today, 25 October some well developed buds were seen on them.  Despite the howling gale that was going on, I managed to get an image of them.  Now all we have to do is to wait for the flowers to develop and then try to identify the species.

Eventually (30 October) a couple of florets opened looking like this.
An orchid expert has confirmed this to be Microtis parviflora.

Quite a few sun-orchids have opened today.  I believe that they are Thelymitra peniculata since they look a bit fatter in the petals than those I called T. pauciflora yesterday!

We now get towards a question.  On 24/10 in the woodland at Dalton the sun-orchids were all wide open when we left just before 1500 hours.  On 25/10, as is usual in this area, they were all shutting up shop by 1345 and were more or less completely closed by 1400.  While most of the local examples are in grassland or Kunzea ericoides scrub I am surprised by this difference.  Why is it so?

I addressed this question to a group of Canberra orchid-interested folk.

Yesterday at a TSR outside Dalton NSW all the sun orchids were still flaunting their attractions at 3pm.  At our place today - as has been the case in past years- they had all shut up shop by 2pm.  Is this due to:
  • the foul weather today (but we have seen the same effect here in past years)?
  • a difference in habitat (grassy woodland at Dalton, Kunzea scrub/grassland here)?
  • Different species of Thelymitra?
  • All of the above?
  • Something else?

One response was " Indubitably yes", which I take to be supporting all of the suggestions, including 'something else'. The most detailed response was from my friend Tony:

Hi Martin
That's like asking what's the meaning of Life, the Universe and Everything.
Temperature, light, humidity and wind are all factors which affect whether the Thelys open their flowers or not. Some like T. pauciflora and related species are reluctant flowerers at the best of times. In my experience, everything else being equal, the flowers don't start opening before 10am and are starting to close again by about 3pm.
Last Friday, when I went out to Mcleods Reserve it was 26C with a gentle breeze and the Thelys were putting on a magnificent display. It was similar conditions on Saturday when we went out with Denis Wison and found T. carnea, T. pauciflora and T. juncifolia in flower. On Monday, same time same location but a few degrees cooler, and none of them were open. Yesterday it was 26C but there was a strong gusty wind which probably explains why your Thelys shut up early.
CheersTony



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