In other plant–fungi alliances the benefit to the plant is evident, though we are not quite so satisfied as to the nature of the quid pro quo for the fungi. We are all familiar with the association between insects and pollen-bearing plants. In the case of bees and flowers the purpose of the partnership is plain. In exchange for nectar and pollen the bee performs the service of pollination. Certain wasps undertake the same office in payment for nectar. But in the case of the orchid (Cryptostylis leptochila) and the wasp (Lissopimpla semipunctata), Nature seems to have excelled herself in her strange methods of achieving her results. Strictly speaking the insect is not a wasp, but belongs to the family of ichneumon flies which parasitise the larvae of other insects. Some of the males do occasionally visit flowers in search of nectar, but in the case under question neither egg-laying nor nectar-feeding was the object of the visits.
Instead of entering the flowers in the orthodox way, thus removing the pollen on its head or back, the insect was observed to enter the flower ‘backwards,’ and emerged with the pollen on the end of its abdomen – always in exactly the same position!
Having satisfied ourselves that this was actually taking place we set about to discover the purpose of such an unusual partnership, the object of the wasp’s visit – the payment it exacted for the service it undoubtedly rendered the orchid.
Close observation showed that the insect evinced no interest in the nectar secreted by the flower, for its head was always turned in the opposite direction; and careful search failed to reveal any larva imbedded in the flower in which it might deposit its egg; and which would act as host to its offspring in its larval stage. We took nothing for granted, and though we felt confident that our wasp was too wise to risk its egg in vegetable matter which might dry long before her larva reached maturity, we made a careful examination of the viscid matter of the orchid, but the microscope showed nothing that we could isolate as an egg.
Then came our biggest puzzle, for a leading entomologist identified our insects as males, so that the egg-placing theory fell through, and we could lay hold of nothing but the one outstanding fact, new, we believe, to science, that the ichneumon fly does, in this unusual manner, perform faithfully the service of pollination for the orchid. It would appear to be a perfect partnership for which the orchid has specially modified its shape.
There is no apparent search on the part of the insect for either nectar or caterpillar, or any evident choice of flower. Possibly possessing keen eyesight or a wonderful sense of smell, the wasp flies directly to the flower selected, taking up the necessary position so easily and surely that one feels it must be answering some natural impulse, whether calculated or mechanical, or obeying some powerful urge. As the orchid matures and when one concludes the moment has arrived for the services of the wasp, the labellum of the flower assumes a strange curve – curiously adapted, one would say, to the needs of the wasp, suggesting a vegetable intelligence that knows and plays upon ‘the passion of insects’. As an instance of insect cunning or obedience to some involuntary prompting it appears unparalleled.
It is without doubt a strange partnership and the benefit to the wasp is still shrouded in mystery.
The solution is no doubt simple when it is worked out, but the season of the orchid having closed further investigations are held up for some months.
Chapter 9
ACROSS THE CONTINENT
‘Looking ahead, the gleaming silver ribbons stretch endlessly as far as the eye can see, merging together on the horizon. At night it seems eerie to travel hour after hour without seeing a single light other than that of the moon or the stars. There is a feeling of unreality about this part of the journey.’
December 1929
Edith presses her face against the window of the train. There is so much to see, from first to last as the train rolls on, mile over mile. The country throws up a succession of sharp contrasts. You never know what to expect around each bend.
They travelled from Adelaide to Terowie, where the land was as beautiful as you please. It rose and fell in softly rounded hills and dreamy pasture lands, so invitingly cool and green. But once they passed Quorn, the land turned dry and harsh.
‘One might think that rain had never fallen in these parts,’ jots Edith in her notebook, ‘were it not for an occasional suspicion of green in small areas that had benefited by slight showers.’
They trek out into the ‘great wastes’ of ‘never never’ country until they reach Port Augusta. From here they head out across the Nullarbor.
‘Not a tree rises above the saltbush or bluebush to break the line,’ Edith writes. ‘By day the sun touches the grey vegetation with a misty purple that is at no time monotonous, and the moon transforms each tussock or bush into strange silver shapes belonging, one fancies, to some other world. Sunrise over the plain is something to remember – a dream of rose and saffron on which the inward vision will dwell for many a day. Here and there white everlasting daisies mantle the ground like a heavy frost. Sometimes patches of pink ones add a new colour note.’
As the train pulls into the station, Edith notices a group of Aboriginal people, upturned palms soliciting coins. Someone throws some coppers which are inspected with a disdainful shrug. They turn their attention to the cook’s quarters, where huge bones are being handed out and carted off with enthusiastic energy.
Further away, an older woman stands, regal and aloof, watching the proceedings with an enviable impassivity. Edith snaps a photo of her through the window and the woman looks up, her expression unreadable before
