The Wasp and the Orchid

by Danielle Clode

Edith first sent Rupp ‘a charming letter’ after he published an article in the Sydney Morning Herald in 1925 on the ‘Cult of the Orchid’. She was soon sending letters and specimens ‘pretty much every week’ – more than any other of Rupp’s correspondents, a communication they maintained until her death.

  ‘She wrote so much for publication that I often wondered how she found time for her private correspondence at all, but her letters were always delightful,’ Rupp declared. ‘Every subject on which Mrs Coleman wrote she illuminated, for she was no merely superficial observer . . . her work has a place in that great fabric of scientific truth . . . and it shall not perish.’

  In January 1927, Rupp finally got to meet his penfriend, spending a couple of days with the Colemans at their Healesville ‘cottage-in-the-bush’, where he also met the photographer Ethel Eaves, whose stereographic photographs of Edith’s orchids and wasps are now in the State Library of Victoria collection.

  Rupp named the doubletail orchid Diuris colemanae in honour of Edith’s work, although this species has now been revised and included within Diuris tricolor. No doubt Edith would have accepted this relegation stoically.

  ‘I agree with you as regards splitting of species,’ she said to a colleague. ‘I take my seat among the lumpers quite cheerfully.’

  Whether to split various forms into new and separate species or to lump them together under a single name is a constant source of contention among taxonomists. Edith believed it took time and careful observation to identify new species among the highly variable orchids.

  ‘In the case of my own species I waited three seasons in each case and saw much material – quite enough to feel sure they were fixed – and entitled to the rank as species. Moreover I based my separation on more than three definite distinctions which are fully apparent in dried material.’

  Today, there are several species named by Edith, particularly from Western Australia, including the green comb or diamond spider orchid (Caladenia dilatata var. rhomboidiformis), the rare smooth lipped spider orchid (Caladenia integra), and the clubbed spider orchid (Caladenia longiclavata). She also named the Victorian graceful leek orchid (Prasophyllum pyriforme).

  In general, her classifications have proven resilient. I’m not sure if the curled-tongue shell orchid (Pterostylis rogerisii), which she named after Dr Rogers, is still a valid name. The Western Australian orchidologists think so but I can’t find it in the Australian Plant Census. The caladenias seem to have been reassigned to a genus Arachnorchis. I ask a taxonomist at one of the herbaria.

  ‘You know we all hate the orchids, don’t you?’ he says to me quietly. ‘Their taxonomy is such a mess and no-one can agree.’

  There was a scientific revision of the group recently but not all of the state native orchid societies accepted it; not all of the revisions were retained. So different names are used in different states. We’re still waiting on consensus. Taxonomy doesn’t always provide the unambiguous answers I’d like.

  I start to wonder what happened to Edith’s collection of dried orchids. I’d imagine her personal collection would have numbered between 100 and 200 different species. It’s about the number of southern orchid species known at the time. It’s also about the size of Rupp’s collection when he donated it to the herbarium in New South Wales. But she would also have collected multiple specimens of different species to ensure correct identification, to account for their natural variation and to trade and share with fellow collectors. The bulk of her specimens might be in the National Herbarium of Victoria – she mentioned in a letter that she intended to donate it to them – but they have no record of her doing so when I inquire there. Not that they would necessarily know. Herbaria are organised around plant species, not their collectors. Personal collections are broken up and distributed through the larger collections, organised into species. Pages with multiple specimens might be split up and reset individually. Collecting details are cut from old pages and glued to new ones, transcribed and amended. Very often pages have multiple entries written in different hands over time. Spare specimens are traded and swapped, their origins sometimes lost in the transactions. There is no way of knowing except by asking the curators to retrieve every individual specimen from their different trays and checking. It’s a lot of work, and they probably have better things to be doing.

  When I search the Virtual Herbarium database, I count 118 specimens – nearly all orchids – that might have been collected by Edith Coleman in the National Herbarium of Victoria, several of which are multiples of the same species. There are another 95 in the state herbaria in Adelaide, 90 in Sydney and 39 in Perth. They probably map her connections: Rogers in Adelaide, Rupp in Sydney and Erickson or Goadby in Perth. A handful are scattered in other collections. It’s not a precise record. The numbers shift each time I count them. Some may be mistranscribed or not even catalogued yet. The database is only as good as the data entered.

  The type specimen for Prasophyllum pyriforme is in Sydney and I come across it by chance, while looking for something else. Its orange folder stands out from the other pale papers. Type specimens define their species. They are usually the first specimen to be scientifically described: the benchmark for future taxonomic studies. Unlike most specimens, this one has a specially made label and a photograph of the living plant. These details are not because it is a type, but because this specimen is from Edith’s own personal collection. Her collection was obviously meticulously organised and professional. I am relieved that at least one of them has survived.

  In 1927, Edith encountered a most perplexing anomaly.

  ‘In early January my daughter described to me certain remarkable actions on the part of a wasp, which she had observed visiting the flowers of C. leptochila,’ Edith explained.

  Cryptostylis leptochila, the small tongue orchid, is a strange flower, even for an orchid. A long, pink, studded tongue curves upwards from a spiked green collar, like a lewd floral punk. It is found only in the eastern half of Victoria, particularly the eastern foothills of Melbourne.

  The type specimen for the graceful leek orchid (Prasophyllum pyriforme) from Edith’s personal herbarium

  The wasp was behaving strangely.

  ‘It entered the flowers backwards instead of in the usual manner of nectar feeding wasps,’ Edith continued, ‘the tip of the abdomen appeared to be embedded in the stigma of the flower, and in every instance, the insect freed itself with a jerk, which shook the stem and suggested resistance.’

  Edith and Dorothy observed the behaviour in Healesville, Upwey and Belgrave. The wasps, which Edith had identified as ichneumonids (Lissopimpla semipunctata), often hunt for larvae among flowers and will also feed on nectar when it is available. But not in this case. On closer inspection Edith was sure that ‘neither larva nor nectar was the object of their visits to the flowers’. Perhaps they were laying eggs? Careful dissection of the visited orchid found no trace of anything that might be an egg. Edith sent her insect specimens to a leading entomologist. They were all male. The mystery deepened.

  By the end of the season, the only facts of which she could be confident were that the insect visited the orchid purposely, entered the flower backwards and successfully pollinated the orchids.

  ‘What then,’ she asked her colleagues in the Victorian Naturalist, ‘was the payment exacted by the insects for the service it undoubtedly rendered?’

  There was a mystery here that needed to be investigated. But the orchids had finished flowering for the year.

  I don’t think Edith knew of any similar observations by other researchers when she wrote about her backwards-pollinating insects in 1927. She says that these observations have ‘so far puzzled several leading entomologists’. I suspect this refers to entomologists she knew and talked to about her observations (like Tarlton Rayment), rather than other published accounts of the behaviour she witnessed. I think she would have mentioned them by name if she had.

  In the intervening winter months, Edith approached her mystery method
ically and systematically. Like any good scientist, she went to the literature and sought the advice of experts. It seems likely that she wrote to Dr. R. J. (Robin) Tillyard, who had recently published the influential Insects of Australia and New Zealand and had just taken up a position, in March 1928, as head of the Council for Scientific and Industrial Research (later CSIRO). At some stage during this process Edith discovered that she was not the first to observe the strange behaviour of wasps and orchids.

  The physical resemblance of many orchids to insects (and indeed some other animals) had been noticed before, as is obvious from their common names. Charles Darwin noted that some of these similarities must be a fluke – like the frog or lizard orchid – but others, with a striking resemblance to the insects that might pollinate them, were too similar to be coincidental. Darwin was not one for coincidences.

  ‘Long and often I have watched plants of the bee ophrys, I have never seen one visited by any insect,’ Darwin mused. ‘Robert Brown imagined that the flowers resembled bees in order to deter their visits, but this seems extremely improbable.’

  Darwin believed (correctly, as it turns out) that the bee orchid, Ophrys apifera, was predominantly self-fertilised. So what then was the point of investing so much energy in such highly decorative flowers? This was Darwin’s great mystery. And if the orchids were self-pollinated, why did bees still visit the flowers, albeit a little bizarrely? The observation, related in a book by Gerard Smith, was worthy of a footnote.

  ‘Mr. Price has frequently witnessed attacks made upon the Bee Orchis by a bee,’ recorded Smith in 1829.

  ‘What this sentence means I cannot conjecture,’ Darwin added in 1877.

  The cause of the sudden explosion of flowering plants into a rich diversity of forms and habits in the fossil record 130 million years ago tormented Darwin – it was an ‘abominable mystery’. And orchids, one of the most beautiful, elaborate and largest of the floral families, were the greatest mystery of all. He devoted a book to them. On the Various Contrivances by Which British and Foreign Orchids Are Fertilised by Insects was published just three years after On the Origin of Species. Perhaps Darwin might have had more luck solving some of these mysteries if he’d looked for more orchids when he was in Australia, instead of platypuses.

  ‘The riddle of those strange attacks has almost certainly been solved,’ replied Edith to the long-departed Darwin in 1928, in a conversation spanning decades and generations, ‘in the first place by Monsieur M. Pouyanne, in Algeria; later, by Colonel M. Godfery, F. L. S at Hyéres, France.’

  And ‘even more conclusively’, she added, by her own research.

  I am stepping carefully into the faintest imprints of Edith’s footsteps, tracing her path through her papers – what she read, what she knew, whom she spoke to and when. The position of a quotation mark or apostrophe, an attribution, a difference in tense from past to past perfect: these tiny details yield major changes in meaning.

  I think it is Godfery’s paper, published in 1925 in the Journal of Botany: British and Foreign, that she has read by 1928. Reference lists will not become a reliable feature of scientific papers for some decades. Like Darwin, Edith names her sources but does not reference them in detail, so I can’t be sure. But she quotes from this paper, uses similar phrases, and the State Library of Victoria has a complete collection of the journal. The 1925 volume is not in my library, though. I have to order it by interlibrary loan. Within a few days, a digital copy arrives from the CSIRO library in Canberra: Tillyard’s library.

  Godfery’s paper is inspired by the ‘brilliant observations’ of Maurice-Alexandre Pouyanne, a French colonial judge in Algiers. Pouyanne’s findings of twenty years of research were published, in French, with the Swiss botanist Henry Correvon, in the Journal de la société nationale d’horticulture de France in 1916 and again in 1923. Godfery’s wife, Hilda, a noted orchid artist, had illustrated Correvon’s book on orchids.

  The trail is long: from Pouyanne in Algiers to Correvon in Switzerland to the Godferys (who lived in Edith’s old hometown of Guildford when they weren’t in the south of France), then possibly via Tillyard in Canberra and finally to Edith Coleman in Melbourne, Australia.

  I can’t find Pouyanne’s original French papers in Australia, so I email a colleague in England. He replies within a few hours, from Atlanta, and says he’ll send me the papers when he gets home in a day or two. The files arrive the next week, along with a translation from the French, which he had commissioned for his own work. What would have taken Edith months, or even years, bounces around the globe in a matter of seconds, minutes and days.

  Colonel Masters Johnson Godfery’s observations were, according to his obituary, ‘carried out by watching cut flowers in vases on hotel verandas in the Mediterranean region’. An endearing image, if a little disparaging. Godfery was an authority on European orchids, particularly Ophrys. By Godfery’s own account he was on his knees, eyeglasses on, closely inspecting a bee clambering backwards into some orchids that he had planted in the hotel’s garden. Having failed to catch the insect with his glasses case, he returned the next day with a net and more success.

  There is nothing obviously bee-like about the sombre bee orchid, Ophrys fusca. It is a simple little orchid, green on top with a two-tone lilac and purple tongue-like labellum. Quite unlike the yellow bee orchid (Ophrys lutea), with its brown beetle labellum, or the bizarrely patterned mirror orchid (Ophrys speculum), which gives every impression of already having a shiny purple insect with long red hairs in residence. But Godfery knew that this little bee entering an orchid backwards was something noteworthy because he had read the papers by Correvon and Pouyanne.

  Pouyanne spent years watching mirror orchids in Algiers, waiting for the perfect conditions: fine, still weather with an abundance of flowers growing close to the burrows from which the female bee-wasps (Dasyscolia ciliata) emerge. Here, too, waited the male bee-wasps, born a month earlier.

  ‘Time hangs heavy with them and they have every leisure to indulge in endless exploration above the hallowed mound,’ explained Pouyanne. ‘To shorten their wait O. speculum give themselves over to entertaining them with certain distractions which are much appreciated by these gentlemen.’

  Pouyanne had no doubts about what was happening.

  ‘The entire insect enters into a kind of paroxysm,’ he said. ‘Its movements and position seem exactly like those of insects engaged in attempting copulation.’

  He suspected mimicry but was uncertain about its nature. The orchid’s iridescent labellum resembles the female insect’s shiny blue wings. The orchids share their hairiness with the bee-wasps. But the orchids still attracted the males even when they were hidden, beneath newspaper or in a cardboard box.

  ‘It would be interesting to ascertain whether the female of the visiting insect has a similar smell,’ commented Godfery.

  In 1928, Edith was back on the trail of her mysterious wasps and orchids, setting out to replace Godfery’s and Pouyanne’s ‘conjectures’ into certainties. By this point she was convinced that the wasps must be ‘answering to an irresistible sex-instinct’. But could she prove it?

  Edith was soon convinced that she was indeed observing copulation. She noticed that the male insects used their modified mating claspers to grip the orchid’s labellum, that their palps, used to deliver spermatozoa to the female, were ‘extruded’ when leaving the flower. And she’d seen a droplet of liquid being expelled from the insects. Mr Arthur Lea, the government entomologist for South Australia, suggested that she smear the droplets on a glass slide and try to draw them. The images she drew were the same as those drawn by Tarlton Rayment when he dissected the male insects and extracted their sperm.

  So, while most flowers offer nectar or pollen in exchange for pollination, these orchids offer sex.

  The notion that plants might lure their pollinators with sex rather than food was certainly unconventional and unexpected and, for many, perhaps a little bit disturbing. Edith must have known she would
have her work cut out persuading others of her conclusions. As the French mathematician Laplace had once said, ‘The weight of evidence for an extraordinary claim must be proportional to its strangeness.’ And Edith’s findings were very strange indeed.

  The strength of Edith’s work lies not simply in her discovery that wasps pollinate orchids by copulating with them, but in the systematic way she investigated and ruled out any possible alternative explanations, amassing a persuasive and convincing body of evidence in support of her theory. Like Darwin’s theory of natural selection, it was the weight of her evidence, not her extraordinary claim, that established her scientific achievement.

  Edith found that the entire structure of the orchid has adapted to accommodate the wasps’ preferences. When the wasp lands on the orchid and clasps the labellum to its underbelly, the upper surface of its body rests on a sticky disc attached to the rostellum, a cap which separates the female stigma from the male anther, preventing self-pollination. Thus glued into place, the insect has to struggle free, a movement which causes the anther cells to open and release their pollen, without coming into contact with the flower’s own stigma. Instead the pollen is transferred to the wasp and transported to the next flower, to be deposited onto the stigma of a different plant.

  An orchid dupe wasp ‘visiting’ a small tongue orchid

  ‘A glance at the strange labellum, modified out of all proportion to the thin, almost thread-like petals and sepals, with its double row of dark glistening glands that gleam in the hot sunshine loved by the wasp, is perhaps sufficient to justify the theory of an attraction based on the resemblance of the flower to a female wasp,’ concluded Edith with some caution. ‘Even to our eyes, the likeness is apparent. To the inferior eyesight of the insect, the resemblance may be still more convincing.’

  The insects could locate a single flower with remarkable swiftness and determination. Having placed some of her flowers in a room, Edith closed the windows so that they would not be pollinated in her absence. On returning a few moments later, she found three wasps on the windowpane and one inside, having squeezed through a tiny crack.