Christmas Bells

Christmas Bells
Christmas Bells - Blandfordia nobilis

Wednesday, December 05, 2007

More Orchids (and Trigger Plants) in Kangaloon.

I am pleased to report that the late flowering perennials (small native plants which are "herbaceous", but persistent, across a number of seasons) which grow along Tourist Road, Kangaloon, have survived the slashing which was given them by the SCA's contractors on 31 October 2007.
Trigger Plant
The main flowers down there, at present are Trigger Plants, Stylidium graminifolium (not Stylidium lineare as I first thought) These cheerful looking plants are waving their pink flowers around on stems about 30 cm high.
(*** Possibly - I have not done a close study, I am sorry.)

With the grass having been slashed recently, of course they stand out, and are clearly visible as one drives along Tourist Road.Some Hyacinth Orchids (Dipodium punctatum*** and *** ***) which were still dormant at the time of the slashing along Tourist Road, Kangaloon, have survived.Many which were already growing then, will have been beheaded - but some have survived. The numbers of Hyacinth Orchids in flower this year is greatly reduced from last year.

These plants have a protruding labellum, (front and centre) which acts as a landing platform for insects, seeking to find the column, which is inside the tube, below the yellow spot, (underneath which the pollinia are located).
These plants grow from large underground tubers, and are hemi-parasitic, surviving by association with mycorrhizal fungi which in turn rely upon Eucalypt trees, close by. They have by-passed the need to produce their own food by photosynthesis, so this species has no true leaves, and no chlorophyll. Its only need to emerge above ground is to be pollinated, and to spread its masses of fine seed on the wind. It lives underground for approximately 10 months of the year. Given what the SCA does to them when they do emerge, that is a pretty clever strategy.

Both these pink flowers, are carried on narrow stems, and can cause some confusion as to what they are. Close examination shows the flowers are very different. Hyacinth Orchids are much larger flowers. This group of Hyacinth Orchids in the forest in Kangaloon is doing very well. Tall brown shoots just budding up.

*** I have corrected a previous incorrect identification of this flower as Dipodium punctatum. DJW 27.12.09
*** *** I have reverted to the original identification after an intensive check of all habitats of the Hyacinth Orchids in Kangaloon and Mount Alexander of which I know. These plants in this clump are definitely D. punctatum. Confirmed on 2 Jan 2010. DJW. I will publish the results of that investigation shortly, on this Blog. 2.1.10.
Trigger Plants have a square looking flower, and close examination reveals they hold out to one side a specialised "column" which is the so-called "trigger". This "column" carries both the anthers, (male organs) and the stigma (female, receptive part of the flower), although the different organs mature sequentially, so the "trigger" is functionally male, first, then, later, functions as the female part of the flower. This structure is well illustrated on the PlantNET site. The "trigger" is movement sensitive. It is on a deep red "handle", positioned on the side of the flower. That "handle" is flexible. There is a deep pink tube inside the ring of paler pink tufts, right at the centre of the flower. When an insect probes inside that narrow tube, (presumably to obtain some nectar) it "triggers" the little "hammer", (clearly visible at the left of the flower) which swings in, to bang an insect on the back while that insect is seeking to collect nectar from the flower. The insect ends up with a dob of pollen on its back, or alternatively, transfers a previously collected grain of pollen from another flower - transfers it (hopefully) to the new flower, thus completing the pollination process. It is possible for an observer to stimulate this reflex action, with a fine piece of grass, probed right inside the tube. The "trigger" will swing over, past the top of the flower. If you were an insect, you can see how the "hammer" would have hit you on the wings, or the top of your head. The plants re-set themselves after a short period of time, so the experiment does not harm the plant in any way.

To coin a bad pun, it is a "hit or miss process of pollination". But judging by the number of Trigger Plants growing on Tourist Road at present, they must be doing something right.

The other Orchid to begin flowering down in Kangaloon at present is the Small Tongue Orchid (Cryptostylis leptochila) There is one particular plant which I have been monitoring for some time. It was budding last week. It opened its first flowers yesterday (4 December). I did not have time to stop to get a new photo, so I will re-publish my favourite photo from last season. I have written previously about the bizarre process of pollination of these Orchids, by male wasps. It is called Pseudo-copulation. You can read about it in my post from 2005.

1 comment:

Gaye from the Hunter said...

hello Denis,

I haven't had the opportunity to get out into the bush lately, so I will enjoy catching up with your nature posts.

Stylidium are one of my favourites. I observed them in numbers in the lower Hunter a few weeks ago, but have never seen them growing this far up the Hunter Valley.

I have observed the trigger in action and it is lightning fast.

I have never observed the Hyacinth Orchid on the valley floor, but have seen it in the wetter areas bordering the east of the Hunter Valley. Your explanation of the Hyacinth Orchid's life is excellent. And I have never seen the Tongue Orchid anywhere, so I'm hopeful to get out and do some exploring soon.