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7 December 2007

Reversal of fortune

Maori legend holds that you daren't speak its name. When digging for it in the forests of New Zealand, its true name of perei must never be said aloud, or the orchid will hear its pursuers coming and hide away. No amount of digging will uncover its delicious tubers then. It was not formed of the earth like other vegetables, but was a gift sent by the gods. The term maukuuku is substituted for the one true name so that the orchid won't be startled...


Tasting somewhat like cinnamon-spiced potato, the underground rhizomes of the Gastrodia orchid have always lured people into searching them out wherever they grow. Ancient Chinese folklore includes the story of an old man who collected Gastrodia in the mountains every spring. One year, after a complete season of searching without finding a single tuber, the man decided to grow the elusive plant himself. He prepared a field, sowed the seeds fine as dust, and waited. A year later the field was still barren - someone must have stolen his crop. At the next planting season, he set up a shack next to his field and proceeded to watch it, day in day out. At harvest time he dug up the whole field without finding a single tuber. The wise old man concluded that the plant must be a gift from heaven, not meant to be cultivated. He named it tianma, meaning 'from heaven', and since that time everybody knew that no mere mortal could ever grow it.

Just by looking at it, one can tell that Gastrodia is no ordinary orchid. It lacks the basic structures that makes things plants, for a start. It has no leaves, no stems, and no roots. All it consists of is a small rounded subterranean rhizome. Infrequently, it will burst into bloom and produce a tall red inflorescence bearing small curious flowers. How does this thing live? Is it magic? How does it obtain nutrients? Why doesn't it need chlorophyll like other plants? Gastrodia is not a parasite, because it doesn't possess structures that enter the vascular tissues of other plants, like the insiduous haustoria of dodder or mistletoe do. It is not a parasite. Or is it? In fact, in a roundabout way, it is. In order to survive, it is entirely reliant on a fungus. This relationship is termed mycoheterotrophy and is a corruption of the symbiotic mycorrhizal relationships between fungi and plants. It is also a pretty neat reversal of the concept of pathogenic fungi that obtain their nutrients from plants. Armillaria mellea is a deadly fungal parasite of trees. Most of its tissues consist of a mass of underground hyphae called the mycelium, which lives off decaying plant matter in the soil. However, when the fungus finds a tree to infect, these hyphae branch out into fibres that resemble black bootlaces. They rapidly form a network under the bark of the tree, slowly taking nutrients from it and causing the tree roots to rot. Once the tree has succumbed, the fungus sprouts edible fruiting bodies from its carcass, the honey mushrooms so cherished in haute cuisine.

In the wild, all orchids need fungi in order to germinate. Orchid seeds are very small, some consisting essentially of only a couple of cells surrounded by a thin layer of protective tissue. A single orchid capsule can release millions of these seeds to the wind, with the chances of successful germination being very slim indeed. When the seed of an orchid encounters a mycorrhizal fungus, a strange thing starts to happen: the fungus enters the seed. At first it looks like the orchid is doomed. However, the tables are turned and the orchid proceeds to receive nutrients from the fungus. Instead of carrying its nutrients with it in the form of a bigger seed, the orchid relies on the fungus to supply its first meal. Cells start to divide, chlorophyll is made, the orchid turns green, and eventually the tiny orchid seedling can photosynthesize and provide for itself. The Gastrodia orchid interacts in such a way with the fungus called Mycena osmundicola to form its rhizome. There it lies in wait for its next encounter. Armillaria is virtually everywhere; it doesn't need to wait long. Soon the Armillaria filaments come into contact with the rhizome underground and proceed to infiltrate it. This was a mistake. It has now signed a contract to provide the orchid with all its nutritional requirements. Energy flows from diseased and decaying trees to Armillaria and on to Gastrodia. It is a parasite-by-proxy. No wonder no-one could ever cultivate it. They didn't realize that they needed the fungus to make it all work.

And yet, in an anthropomorphic way, it is as if the orchid has not forgotten its kinship with the other plants it indirectly feeds upon. It reduces the voraciousness of the fungus by the clever use of chemical signals. These fungal inhibitors protect uninfected trees in the forest surrounding the orchid from falling victim to the Armillaria's gluttony. It seems the orchid has planned for the wellfare of its future offspring as well.
Recently, five new orchid species were discovered in the Green Corridor, central Vietnam, by the WWF Vietnam programme and the Forest Protection Department of Thua Thien Hue Province. One of these is a brand new Gastrodia - pictured here - named Gastrodia theana after its discoverer, Vietnamese botanist Pham Van The. With warty pink petals that barely open to reveal a reddish lip lurking within, it really is a bizarre addition to the orchid family. It would be easy to believe that it was listening to every word we say. How soon before this one starts its own mythology? Perhaps it already has a MySpace page.

19 comments:

Wuttisak said...

Nice blog. I will keep reading. Please take the time to visit my blog about Orchid Care

The Electric Orchid Hunter said...

Thanks, although this is your second comment, and it is identical to the first. Also, your blog seems to consist of cut-and-paste bits plagiarized from other orchid sites. Please do not spam me again.

Church Lady said...

(I left something for you on my blog)

:-)

I will drop by later to read today's entry.

Inarticulate Fumblings said...

That was really interesting. The artist in me couldn't help but start writing narrative regarding the little man that set up a shed to protect his crop. I'm on my way to research what's been written about him.

Claire said...

Absolutely fascinating! Gastrodia sounds very interesting. How do commercial growers cultivate all the common orchids you can buy? They must have somehow mastered dealing with the host fungi or perhaps there's another way. My firebelly toad habitat's single orchid had a 'baby' and the parental unit died. I am hoping to get the youngster to bloom.
May I link to you?

morbidneko said...

they just dont teach this stuff in schools...

The Electric Orchid Hunter said...

church lady: thank you. See you soon.

IF: it's a pretty sweet story, isn't it? I like the Maori take on it as well; it bears many similarities to European superstitions about mandrake. Did you see a movie called Pan's Labyrinth?

claire: I appreciate all links and will reciprocate. I knew someone was going to ask that question. In the 60s, the wonders of tissue culture were invented. All commercial orchids are first grown in flasks, the seeds sown on a special kind of jelly that contains all the nutrients they need. It's all very science-y and requires sterile lab conditions. Before that, the only way people could get the darn things to germinate was by sowing the seeds directly around the wild-collected mother plant; hopefully some of the fungus would have come along for the ride and will inspire the seeds to sprout. Look for some flasks at your next orchid show; sometimes you can even purchase a flask of your own orchid babies! Be warned though: the germination rate is much better than in the wild - you might find yourself overwhelmed by teeny-tiny orchids!

morbidneko: would the kids pay attention if they did?

wreckless said...

I'll have to come back and re-read this when I have more time.
Scanning it, it looks to be mighty interesting.

gm said...

Jy's darem kwaai met die spammer! Lag.

Dit is 'n fassinerende een - ek het dit al 'n paar keer deurgelees en dit bly ongelooflik. (Almal fawn altyd in jou comments, maar met goeie rede).

Ek verstaan ook hoekom orgidee so gewild is: hulle is baie seksueel. Daai eerste foto is besonders fallies. En ander orgidee, wel, praat vir hulself. Ek sal graag jou siening wil hoor...

mike said...

I love the new (new to me!) title bar on your blog.

SleekPelt said...

Another good one, Teoh. I saw and liked Pan's Labyrinth, but I don't remember it well enough to get the connection. We'll watch it again sometime and I'll pay more attention.

Aine said...

Another fun, informative post! A plant that takes advantage of a fungi-- how cool is that!! Those nasty fungi, always leeching off those around them....

Gotta love when an organism is egocentric enough to send off seeds without food in hopes that some other organism has expended lots of energy making food that the seedlings can eat. (Kinda sounds like some parents I know...)

When I think back to Bio classes I remember all the times profs would personify plants. It's a great way to bring the science to life. Too bad not as many high school teachers do it-- more non-science students might enjoy learning about biology. (Hey-- you'd be a great science teacher. Do you want a job? My daughter's school could use some great teachers. :))

Pan's Labyrinth is on my list of films to see. Your mention of mandrake made me think of JK Rowling's use of mandrake in Harry Potter. The young seedlings' roots look like human babies and their cry is fatal (not that I can relate, as a parent-- LOL)

Thanks again for the brain stimulation!

Inarticulate Fumblings said...

Hey... sorry, this has nothing to do with this post. I'm wondering how you put Dalyn's bruiser.png onto your blog. I want to do the same for her and can't figure out how to do it.

Church Lady said...

I finally had the chance to read this in a quiet place and thoroughly enjoyed it.
I am amazed, like Aine, that seeds are sent out in a somewhat arrogant nod to nature--somehow knowing they will survive.
Very interesting post.

sonkind said...

Geseende Kersfees en 'n "Magic" 2008 vir jou!

Church Lady said...

Happy Holidays, EOH. Hope you and your loved ones have a chance to unwind and enjoy the real pleasures of life.

:-)

singleton said...

Honestly, reading these pages is like discovering ancient ruins, the walls covered with mythological stories, that somehow lead us to another world, a real world, right under our fingertips! It blows my mind how you somehow manage to not just capture science and magic at once, but mix it into a captivating read! Happy Holidays Electric, wishing you all the wonder in the World!

Trundling Grunt said...

Wow.

Have a good Christmas, wherever you are.

Anonymous said...

Interesting!