Category: Wildflowers Orchids

Leaping and Lazy Spider Orchids

10/10/2021

Greetings fellow Foxies,
I have been wandering around Foxes Lair since about 1990 but still make new discoveries. Last year i found a single leaping spider orchid (Caladenia macrostylis). Unfortunately, this beautiful double-header is in a public spot and was picked this year, I still pondering on protection measures. It is yet another of the Foxes Lair orchids, which is an only plant or in only one spot.

Caladenia macrostylis

This season I stumbled upon a group of lazy spider orchids (Caladenia multiclavia) in the district. They are amongst the most ornate orchids I have seen, particularly when the sun is behind them. They are also very hard to see in their natural habitat. While very carefully placing dead branches around to protect them, I inadvertently stepped on one. Their location will remain secret as they are locally rare.

The lazy spider orchid's insect-shaped labellum indicates that it tricks flower wasps into pollinating them, as does the dragon orchid (Caladenia Barbarossa).
Even more exciting was a find in this reserve of the Bent Spider Orchid, which is a Caladenia multiclava /Caladenia polychroma hybrid

Bent spider orchid

Caladenia polychroma

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The intriguing article below tells how spider orchid species could have evolved from general insect pollination to targetting flower wasps.

The article inspired me to collect images below of spider orchid flowers that show changes in glandular calli (raised, fleshy growths on the labellum) to resemble a female flower wasp more closely.

Caladenia chapmanii

Caladenia longiclavata

Caladenia macrostylis

Caladenia discoidea

Caladenia multiclavia

Caladenia barbarossa

Spiculaea ciliata

The ultimate is the flying duck orchid. I have discovered that there is a species in the district and hope to hunt it down next year.

Another specialist is the elbow orchid Spiculaea ciliata, which flowers on and around granite outcrops

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Unlikely Place for orchids

9/10/2017

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Greetings fellow Foxies,
I was surprised recently to see orchids in bare and dry bark covered soil under wandoos and powderbarks in Dryandra Woodland Candy Block. Small and relatively inconspicuous Wandoo Beard Orchids and Frog Greenhood Orchids are tough customers that are adapted to drier environments. The Wandoo Beard Orchid (Calochilus stramenicola) has reduced petals and sepals that only partially open and a dense bearded labellum. Calochilus means"sweet lips".They may only open for a day or two while emitting a pheromone to attract large male Scoliid wasps. My colleague Lyn Alcock caught the image of a desperate male wasp attempting to enter a partially opened flower. If the wasp didn’t return the next day, the flower may have pollinated itself and closed.

Not fair! As a fellow male I express solidarity with the poor fellow.

does the interior resemble a female wasp?

male wasp desperately attempting to mate

With these were several tiny but very healthy Frog Greenhood/ Pterostylis sargentii orchids flowering in Foxes lair in August!) and a single blue sun orchid about to open. The Scented Sun Orchid/Thelymitra macrophylla is relatively common in Foxes Lair in mid- late October including some tough places like two that flower in a marri log on the Banksia Walk.

Frog Greenhood Orchid at Candy Block

Scented Sun Orchid

South African Orchids are also occasionally found in tough places like that about this time.

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Bird Orchid Pterostylis barbata

24/9/2017

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I was excited to find a bird orchid at Newman Block south-east of Highbury, because I hadn’t seen one for 65 years. My interest in wildflowers began then when my mother and I used to look for orchids in remnant bush at Karrakatta Cemetery. Alas now all graves.
This orchid has always fired my imagination with its elegant shape, translucence and the strange wispy labellum that gives the species name. Barbata means beard.
with wispy labellums and elegant shapes, plumed greenhood orchids are the most evolved of the Greenhood orchids.
In this case the galea (hood) is folded inwards to form the entry and exit spots for gnats with essentially the same column tube and anther location.
Unlike most greenhoods, the bird orchid is pollinated by a tiny predatory fly dagger fly Emis species). Male flies present a gift to females (dinner date?). The image taken from this reference, shows a male presenting to an orchid.

Wait, there is more to this plant!
The leaves have a wonderful reticulated and variegated green, which resembles a tropical plant. Delightful!

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Shell and Jug Orchids

23/9/2017

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Greetings fellow Foxies,

After dissecting greenhood orchids to see how they trapped insects I moved on to shell and jug orchids that have a more open appearance. In the shell orchid image below one can see that the lower two sepals are upswept rather than being down to form a landing platform, the hood is more open, and the labellum is much skinnier. A few deft slices of my trusty scalpel revealed how this unlikely combination could force an insect to pollinate the flowers. Near the base of the interior the hood petals fold in and the labellum widens to seal the chamber containing the column tube.
In the cross-section below the labellum is closed, but if you picture it leaning forward, imagine a male gnat crawling down it, following the plant-made scent of a female (pheromone).
When the gnat get to the base, the labellum snaps forward, forcing it to climb the column (leaving behind pollen attached its body), through the tube where it gets another dose of pollen, and out of the flower.
Can you see a gnat that was trapped by a curly bit at the base of the labellum? It is the remains of a Fungus Gnat (rather appropriate that it has been consumed by a fungus), whose maggots consume mushrooms, but more of this below.

Pterostylis hamiltonii Red-veined Shell Orchid

Arrows show gnat's journey through the flower

The Jug Orchid, Pterostylis recurva has an even more open- looking structure than shell orchids, but it is just a modification of the shell orchid layout.
It has the same infolded petals and thin labellum with widened base and little horns at the top of the column tube to position the labellum when closed.

Pterostylis recurva Jug Orchid

Front and side section

Note the gnat trapped by a strange basal labellum structure. I originally thought that the evil looking hook was meant to poke the gnat in the bum if it tried to reverse down the column, but now suspect a more sinister purpose. The hook itself could stop the labellum from snapping too far back, but the fork underneath seems to be designed to trap insects, as does the curved projection in the shell orchid and the big donger in the Frog Greenhood.
An associate doing a PhD on greenhood orchid pollination agreed with me that evolution rarely produces intricate structures like this for no reason, but said that insect deaths may be collateral damage if the plant is successfully pollinated anyway. Is the hook just a fancy counterweight?
In the image below the column is smeared with pollen, so other gnats had been safely through this flower before this poor individual met its end.

However the mouldy gnat in the shell orchid reminded me that orchids require fungi to form a mycorrhiza. IF the mould spores could serve this purpose, this would be a neat way for these orchids to inoculate their seeds.
Who knows?

Gnat trapped in Jug Orchid

Gnat remains in Red-veined Shell Orchid

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Plain but Ingenious Greenhood Orchid

21/9/2017

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Horizontal galea Pterostylis concava

Greetings fellow Foxies,
Greenhood orchids (Pterostylis species) look plain but their flowers are little marvels of nature, which trap insect pollinators (mainly Mycetophilidae and Sciaridae families, commonly known a fungus-gnats and dark-winged fungus-gnats respectively). The hood called a "galea" consists of the dorsal sepal fused with two lateral petals. The galea curves forward to form a light-filled chamber containing the column. The column, which contains the sexual parts of the flower (stigma and pollinia) has wings which fold around to form a tube.
The lower sepals are partially joined make a landing platform on which, the lower highly modified petal, the labellum closes the trap when gnat passes over it.

There are two basic galea orientations. Local examples are

Horizontal galea with a short labellum:- dark banded greenhood orchid P. sanguinea, frog greenhood orchid P. sargentii, cupped greenhood orchid P. concava, and painted rufous greenhood orchid P. picta.
Semi- vertical galea with long labellum:- jug orchid P. recurva, red-veined shell greenhood orchid P. hamiltonii, hairy stemmed snail greenhood orchid P setulosa, bird orchid P. barbata.

Vertical galea P. hamiltonii

Vertical galea P. setulosa

Vertical galea P. recurva

Vertical galea P. barbata

Male gnats are attracted to flowers by a female pheromone scent, and walk over the labellum, which snaps shut and traps them. Light from the translucent galea above guides them through the column tube where they press against the stigma and pollinia to fertilise the flower then attach a pollen sac to the gnat's back.
The labellum is a miracle of evolution: a petal which has changed into a tiny trapdoor with an attachment on its base called a lure, and a hinge attachment. The lure is a counter-weight and pheromone emitter. I noticed that jug and shell orchid lures had pinned and killed unfortunate gnats that triggered them.

Pterostylis sargentii

Pterostylis sanguinea

Pterostylis picta

P. hamiltonii interior of flower

When a gnat crosses the labellum it snaps shut against the column. To escape, the gnat climbs up the light-filled hood, through the tube in the column and squeezes past the pollenia. Hairs at tube entry stop the gnat moving backwards. Arrows in images below show a gnat's journey through the flower.
If the labellum shuts and the flower is not pollinated, it reopens in ten to thirty minutes.