Acianthella Orchids found at Gerroa.- update - Identity confirmed

A contact of Alan Stephenson's, Matthew, first discovered these plants last year, while working on "bush regen" work in the sand dunes in the Littoral Forest at Gerroa. Alan and I saw some of these plants last year, but the flowers had finished. I reported on the plants, with seed capsules present, on 15 June last year (much later than this year). That tells you something about the strange seasons we have been experiencing over the last few years.

Matthew contacted Alan yesterday to say that they were in flower again, (in fact mostly they had finished). But we went there today, met Matthew and took some photos of a few open flowers.

Front on view of Acianthella at Gerroa today.

Side on view of the Acianthella flower at Gerroa
The flower structure is clearly similar to
Acianthus exsertus

The whole plant is only about 2 inches high (about 50 mm) and the flower is less than 3mm across (slightly larger than a match-head). The front-on image when viewed at maximum pixels (as uploaded here) is about 50 times larger than the original flower.

That cropped image allows one to see the fine details of the flower, which is green except for the slightly rude looking pink cap of the anther (the male reproductive part of the flower). There is nothing subtle about Orchids!

These plants are presumably self-pollinating (at least David Jones's Big Book says so).

Plants growing in leaf litter on Littoral Sand Dunes
(2 plants circled in red)
Click to enlarge.

The shot of 2 plants growing amongst the leaf litter (circled in red) shows them at more or less real size (if viewed at full pixel size), if you are viewing this on a computer (smaller if seen on an I Pad).

The side-on view shows more clearly the structure of the flower which is clearly closely related to the more familiar Acianthus exsertus . The leaves are different though, much softer and not reddish underneath, and shaped almost like a "Club" (as in a pack of playing cards). The leaves are held above the ground (as is Acianthus). 

The tiny size of the flower is what surprised me most. At least Acianthus can be clearly examined with an un-aided eye. Not so these things. I had to use the camera, take a shot and then examine the image, to know if the flower was even properly open.

On the balance of probabilities, these plants are likely to be Acianthella amplexicaulis. I say this as, despite the difference in geographical range from what has previously been reported for that species, the photos I took look very similar to the ones Colin and Mischa Rowan have photographed. But their website does not show a location for their plants.

In that case this is still an important records, as a major extension of range - as previous records apparently are all north from the Hawkesbury estuary.

http://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Acianthella~amplexicaulis

Thanks to Matthew and Alan for showing me these plants.

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UPDATE 10 April 2013

Alan Stephenson has advised:

Have just spoken with Mark Clements and the orchid is definitely Acianthella amplexicaulis. This means it is not a new species but an extension of range of about 250 km and Mark was very pleased to get the samples. 

Thanks to Mathew for the find, as it is important.

Regards

Alan

That confirms my impression of the similarity of my images of these Orchids with those of Colin and Mischa, and of Bruce.

Good to have the ID confirmed, none-the-less, given the extension of range involved.

Once again, good work by Matthew in spotting these tiny things in the first place and in reporting them to Alan Stephenson. Thanks also to Mark Clements for the positive ID of the specimens.

Acianthella Orchids at Seven Mile Beach National Park

These plants have been known of for at least a year, when they were first reported by Matthew, in charge of a Landcare Group. 

He spoke with Alan Stephenson last year, who inspected the a few of these unusual plants, and concluded that they are a species of Acianthella. Little more is known about these plants, as they have not yet been found in flower.

Today I went with Alan and Matthew to again look for these plants, and we found quite a lot of them - approximately 50 plants in all.

The plants we found today were scattered around on the moist leaf litter of coastal mixed Eucalypt, Banksia and Casuarina forest and rainforest understory species, growing on sand dunes, behind Seven Mile Beach.  

Even for three quite experienced orchid people, they were hard to find.

This was the first of these Acianthella plants I saw today.
The leaf is held well off the ground
above the leaf litter
Growing over moist sand.
The lead surrounds the flower stem,
but it is classed as "sheathing" the stem.

CLICK ON IMAGE TO ENLARGE IT.
"Sheathing" is illustrated in Figure g
Source PlantNET Glossary

These plants hold the leaf off the ground, just above the leaf litter. 

A non-flowering plant
showing the lobed leaf shape.

A very young, non-flowering plant.
The leaf has not developed the distinctive lobed margins
but it clearly shows the notch
where the leaf is attached to the leaf stem.

Some of these plants had already flowered, but obviously their flower stems are very small, compared to their nearest relatives, the Acianthus genus. We saw lots of leaves of Corybas and Acianthus and many, many colonies of Pterostylis, but the Acianthella are much smaller in leaf and flower than any of those common Orchids. 

Seed capsules clearly visible
CLICK TO ENLARGE IMAGE.
There are two separate Acianthella plants growing closely together.

The leaves are very distinctive in texture and shape.
They are more or less club shaped (as in the cards of that name).

Juvenile plants sometimes have lobed leaf margins.
In more mature plants the lobes of the leaves can be quite pointed.

Leaf is 2 cm long,
with noticeable points to the leaves.

Leaf is approx 13mm wide.
There are two Acianthella plants growing side by side
Both have set seed.

As yet, we do not have any diagnostic details to identify the species of these plants.
 
The books report that the Acianthella genus is restricted to two species in Australia, and five species in New Caledonia. The Australian ones are one from north Queensland and Acianthella amplexicaulis is reported to extend only as far south as the littoral rainforest, north from Wyrrabalong National Park (just north from The Entrance, NSW).

So, if and when these plants are identified, then it will at the very least be an extension of the range, if the species is confirmed as Acianthella amplexicaulis.
 
However, it is also possible that these plants might be identified, in due course, as a new species in the genus Acianthella. As no flowering plants have yet been found, and recorded, it cannot be identified beyond the genus level at present.

That's a further challenge for next year.

Seven Mile Beach Orchids just starting up

The Orchids of Seven Mile Beach National Park are just starting up their New Season of flowering. By that, I mean the Autumn and Winter Orchids, of course.

The sandy walking track from the main parking area, (roughly opposite Beach Road - coming from Berry) parallel to the beach (and the road) runs for approximately 1.5 Km, and it houses perhaps the most dense collection of Corysanthes (formerly known as Corybas) and Acianthus plants which I know of (over such a large area). We also found some of the Cobra Greenhoods (which I have also found in the Southern highlands in the previous week), a few Bunochilus (Tall Greenhoods) and one lonely Petalochilus pictus (Formerly known as Caladenia picta)

To me, finding this flower, Petalochilus pictus is always exciting
Not only is it very attractive,
to me it represents the precursor, the harbinger,
of the winter/spring flowering Orchids.
It typically flowers from May to June.
The related flowers in the Highlands
flower through to November.

The Corysanthes are perhaps the most interesting for me, as these plants do not seem to grow in the Southern Highlands (to the best of my knowledge).


Corysanthes fimbriatus were just in flower, whereas some Corysanthes pruinosus were still only at the budding stage. PlantNET seems to indicate "Cor. fimbriatus" does grow west, to the Dividing Range, but I have not yet seen it in the local area.

Deeply hooded flower of Corysanthes fimbriatus

The same flower Corysanthes fimbriatus seen laterally.
The base of the flower has an arch (a "boss")
then a fringed rim
The hood encloses the tube
leading down to the centre of the flower

.

Acianthus fornicatus

This is why I referred to it as tall.

The leaves of Acianthus are held on a stem, normally,

but seldom are the leaves as far off the ground as this one is.

Mobile phone for scale shows how high off the ground
the leaf of this Acianthus fornicatus was.

Diplodium grandiflorum
(the Cobra Greenhood)
showing the flared edges of the hood.