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native orchids

What leads intrepid explorers and indolent couch potatoes alike to an obsession with orchids? One expert attempts to find an answer.

STORY: IAN ST GEORGE

Orchids belong to one of the most common plant families. Yet, some orchids are indeed vanishingly rare and undeniably beautiful, and many are well nigh impossible to grow in cultivation. In the wild, in our temperate zones, they are, furthermore, exquisitely small and delicately coloured – jewels of the forests and swamps and scrublands. That makes them special.

When I was a young man, my mother divided up the rather ordinary cymbidium she had inherited from our grandmother and gave each of her children a pseudobulb. I stuck mine in a pot, sat it under a tree in our Dunedin garden and promptly forgot about it. Five years later, she died and when I checked her cymbidium, it looked as if it would soon follow. The public library had no books on how to rescue a moribund cymbidium and of course we had no internet in those days, but a friend told me there was an outfit called the Otago Orchid Society and they might know how to save it.

I attended their next meeting, but to my surprise the speaker talked about wild orchids in Otago. I had no idea we even had such plants but they struck a chord with me. Tiny gems of the bush, they appealed to my budding interest in macrophotography, my desire (inherited from my father) to be in the bush and my pedantic pleasure in rather fussy drawing.

I joined the ranks of the obsessed: I photographed them, I dissected them, I drew them, I read and wrote about them.

At about the same time, a group of like-minded devotees started the New Zealand Native Orchid Group and I met and listened to aficionados with an immense collective knowledge of the plants. I read and studied what they wrote.

I have searched for wild orchids in many temperate zone countries. On sabbatical leave in England, I looked up David Lang, author of books on British orchids and a vet in east Sussex. He took me out to see orchids in his local spots, but he also gave me written instructions to more distant sites where relative rarities grew. It was like a treasure hunt with all the thrill of anticipation and it took me off the beaten track to new and interesting places in England, Wales and Scotland at the weekends.

I have enjoyed the delight of finding wild orchids in the US, France, Spain, Italy, Switzerland, Canada and Australia with new friends – some intrepid and some indolent.

The surprising world of native orchids

We are, let’s face it, a botanical colony of Australia and many New Zealand orchids are only subtly different from their Australian counterparts. Perhaps some were shared in Gondwana, but many are more recent arrivals, their dust-like seeds lifted high into the warm air before being blown over the Tasman Sea in the prevailing westerlies.

The recent decades have been an exciting period in New Zealand orchidology. In 1980, we had less than a hundred recognised species and 50 years later, by the end of the 2020s, I expect we will have almost twice that number.

This huge increase in knowledge and numbers results from dedicated study by professional botanists, often informed by the work of enthusiastic amateurs “gazing with a trained eye” out there in wetlands, old pastures, bush tracks, mānuka scrub and mountains. More importantly, it has been a period of increasing ecological awareness, with escalating conservation consciousness and effort leading to better knowledge and preservation of habitat for some of our rarities.

A Northland tongue orchid, Cryptostylis subulata, appeared some years ago from Australia. Its specific pollinator is an ichneumonid wasp and without it the plants would have had little chance of survival – but the wasp arrived too and now the orchid is thriving. Also, a colony of the ant orchid Chiloglottis trapeziformis is thriving in pine forest on the west coast north of Wellington.

Other Australian species have made landfall here, survived for a while, then died out, perhaps because specific mycorrhizal fungi required for nourishment or insect pollinators are missing.

The recent decades have been an exciting period in New Zealand orchidology. In 1980, we had less than a hundred recognised species and 50 years later, by the end of the 2020s, I expect we will have almost twice that number.

Many plants do need insect pollinators, so a symbiotic relationship develops in which the flower rewards the insect with honey or pollen and the insect rewards the plant with cross pollination. No such symbiosis for orchids: they cheat – and they do it in various ways.

Orchids are characterised by a floral structure called the column, an organ with male anther above and female stigma below. Pollen from an anther must be transferred to a stigma for fertilisation to take place. Cross fertilisation requires an insect.

Cryptostylis exudes scents similar to the pheromones female wasps use to attract males and the underside of its labellum even looks rather like a wasp. Males approach the flowers from downwind and, besotted with the pheromones and visually attracted by the labellum, attempt sex with it and with all that movement dislodge pollen and take it to the next flower. This is called pseudocopulation and it is a common deception among orchid species. Native bees do it with sun orchids (Thelymitra) columns; fungus gnats do it with many New Zealand greenhoods (Pterostylis) and spider orchids (Corybas). The orchids get pollinated; the hapless insects get nothing.

Some of our spider orchids appear to attract gnats by smelling like the fungi in which the gnats normally lay their eggs: female gnats visit and deposit eggs in pockets in the orchid labellum, meantime pollinating the flower. This is called brood site deception.

For many other New Zealand orchids though, we just don’t know what pollinates them or why.

Some Ophrys orchids in Europe have flowers that resemble male bees and when real male bees try to fight them off, pollen becomes attached and carried on to the next imagined interloper.

One feature of the New Zealand wild orchids is a fallback self-pollination mechanism and that may have evolved because of the relative scarcity of insects here. Some greenhoods have an upright stance and a bulbous stigma so pollen falling from their own anther catches and sticks to the stigma. Some potato orchids (Gastrodia) have anthers and stigmas in such close proximity that it seems the only way they can reproduce is by self-pollination; the pendulous flowers of other Gastrodia tilt upwards and allow their own pollen to fall onto their stigmas. Sun orchids that remain unfertilised close up and self-pollinate. Some Corybas also have stigmas directly below the pollen, indicating at least the capability of self-pollination.

One feature of the New Zealand wild orchids is a fallback self-pollination mechanism and that may have evolved because of the relative scarcity of insects here.

Why are some orchids so rare?

Habitat destruction by development for farming and building is the main reason that a number of our wild orchids are extremely rare, though some may have been gathered to the point of extinction by overly avid collectors.

The swamp helmet orchid Corybas carsei, for instance, was discovered in swampland north of Kaitaia but disappeared from that site when the swamps were drained. It has been rediscovered in a secret Waikato swamp, its only known site now, where it survives precariously, the subject of intense research efforts to help it reproduce and survive.

The ant orchid Chiloglottis formicifera was collected in large numbers near Kaitaia in the early 20th century but has never been seen in the wild in New Zealand since, perhaps because the remaining numbers were too low for reproduction, perhaps because the pollinator was absent, perhaps because the associated fungus was absent. We cannot be certain. It is, happily, not rare in Australia.

There is no doubt, however, that overzealous collection can severely reduce local numbers. I have taken “interested” groups to look at my favourite orchid sites only to find, a week later, spade holes where the orchids used to be.

I think greater awareness of ecological values, along with knowing how difficult many wild orchids are to grow, has diminished that thieving propensity. It has also reduced the number of advertisements for wild orchids for sale (there was only one on Trade Me today).

Can I cultivate native orchids?

Wild terrestrial orchids vary in their ability to extract nutrients from the soil. A few will survive when transplanted, but many will not: they require one or more specific fungi in the soil to form mycorrhizal associations and supply nutrients. That is one important reason they are hard to grow. It’s best to leave them in their natural habitat where everyone can enjoy them.

If their habitat is to be destroyed, try to transplant them to a suitably similar habitat. Only if you are an experienced grower should you take them home to try to save them.

The place of “conservation by cultivation” is not yet well understood. There have been no large scale successful attempts at the salvage-cultivation-reproductionreplanting cycle here. There is much to learn yet. If you want to contribute or just want to know more about our orchids, join the New Zealand Native Orchid Group, which has a pocket guide for sale. Membership secretary is Graeme Jane (gtjane@kinect.co.nz). More info on the group’s website (nativeorchids.co.nz) and Facebook (look up NZ Native Orchids). You could also look up the NZ orchid pages on iNaturalist (inaturalist.nz/projects/new-zealand-native-orchids).

NATIVES

en-nz

2022-11-01T07:00:00.0000000Z

2022-11-01T07:00:00.0000000Z

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