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| Our new spot until Friday. |
We shared a Mole Burrito that was both stupendous and stupendously cheap. As for cribbage, Stumpy is up 2-1 in the Phoenix Open.
The orchid blooms last night.
We animals don't give plants nearly enough credit. "A vegetable" is how we refer to a person who has been reduced to a condition of utter helplessness, having lost most of the essential tools for getting along in life. Yet plants get along in life just fine, thank you, and had done so for millions of years before we came along. True, they lack such abilities as locomotion, the command of tools and fire, the miracles of consciousness and language. But the next time you're tempted to celebrate human consciousness as the pinnacle of evolution, stop for a moment to consider exactly where you got that idea. Human consciousness. Not exactly an objective source.
So let us celebrate some other pinnacles of evolution, the kind that would get a lot more press if natural history were written by plants rather than animals. I'm thinking specifically of one of the largest, most diverse families of flowering plants: the 25,000 species of orchids that, over the past 80 million years, have managed to colonise six continents and almost every conceivable terrestrial habitat, from remote Mediterranean mountaintops to living rooms the world over. The secret of their success? In a word, sex. But not exactly normal sex. Really weird sex, in fact.
Hoping to observe some of this plant sex, the photographer Christian Ziegler and I recently journeyed to one of those remote Mediterranean mountains in search of one of the most ingenious and diabolical of these orchids: the Ophrys, or, as it is sometimes called, the bee orchid. (Some botanists, less politely, call it the prostitute orchid.) I'd been eager to lay eyes on this orchid and meet its hapless pollinator ever since reading about its reproductive strategy, which involves what my field guide called "sexual deception" and "pseudocopulation." What I learned forced me to revise radically my estimation of what a clever plant is capable of doing to a credulous animal.
In the case of this particular Ophrys, that animal is a relative of the bumblebee. The orchid offers the bee no nectar reward or pollen meal; rather, it seduces the male bee with the promise of bee sex, then ensures its pollination by frustrating the desire it has excited. The orchid accomplishes its sexual deception by mimicking the appearance, scent, and even tactile experience of a female bee. The flower, in other words, traffics in something very much like metaphor: this stands for that. Not bad for a vegetable.
Orchid hunting sounds arduous, and in many places it is, but in the mountains of Sardinia Ophrys orchids grow like roadside weeds. Though they're only 8ins or so high, when they bloom in April you can spot them from a moving car. Even close up, the lower lip, or labellum, of these diminutive orchids bears an uncanny resemblance to a female bee as viewed from behind. This pseudobee, which in some Ophrys species comes complete with fake fur and what appear to be folded iridescent wings, looks as though she has her head buried in a green flower formed by the actual flower's sepals. To reinforce the deception, the orchid gives off a scent that, though imperceptible to us, has been shown to closely match the pheromones of the female bee.
It works like this. The male bee alights on the bee-like labellum and attempts to mate, or, in the words of one botanical reference, begins "performing movements which look like an abnormally vigorous and prolonged attempt at copulation". In the midst of these fruitless exertions, the bee jostles the orchid's column (a structure unique to orchids that houses both male and female sexual organs) and two yellow sacs packed with pollen (called the pollinia, another structure unique to orchids) are stuck to his back with a quick-drying glue-like substance. Frustration mounts until eventually it dawns on the bee that he has been had. He abruptly flies off, pollinia firmly attached, in frantic search of more authentic female companionship.
There was something poignant about the solitary bee I spotted, flying around madly with what looked like a chubby pair of yellow oxygen tanks strapped to his back. He'd been deluded by the promise of sex – bee sex – when in fact all that was really on offer was plant sex. Botanists have been known to refer to pollen-carrying bees as "flying penises," but of course most of the world's bees perform that role unwittingly, with food rather than sex on the brain. Not so for the poor, deluded orchid bee.
In fact, the sexual frustration of the bee turns out to be an essential part of the orchid's reproductive strategy, which is to favour mixing one's genes with distant mates. (Preferable, since inbreeding decreases fitness.) When a bee has been discombobulated by sexual frustration, it's much less likely to mate with a flower on the same or nearby plant. Determined not to make the same mistake again, the bee travels some distance and, if things work out for the orchid, ends up pseudocopulating (and leaving his package of pollen) with another orchid. That distant orchid is likely to look and smell ever so slightly different from the first, and some botanists believe these subtle variations from plant to plant are part of the orchid's strategy to prevent bees from learning not to fall for the same flower twice. Think of it: the very imperfection of the orchid's mimicry may itself be part of the perfection of its reproductive strategy.
The pollination strategy of the Ophrys is, like that of so many orchids, ingenious, intricate, wily, and seemingly improbable – so much so that proponents of intelligent design sometimes point to orchids as proof that the hand of higher intelligence must be at work in nature. Though some orchids offer conventional food rewards to the insects and birds that carry their pollen from plant to plant, roughly a third of orchid species figured out long ago – unconsciously, of course –that they can save on the expense of nectar and increase the odds of outcrossing by evolving instead a clever deceit, whether that ruse be visual, aromatic, tactile, or, in the case of the bee orchid, all three at once.
The deception and exploitation of animals has become something of an orchid family speciality. There are orchids in the genus Orchis that lure pollinators with the promise of food by mimicking the appearance of nectar-producing flowers, or, in the case of fly-pollinated Dracula orchids, by producing an array of nasty scents running the scales of putrefaction, from fungus and rotten meat to cat urine. (Believe me, I've sniffed them.) Other orchids, such as the Serapias, promise shelter by deploying floral forms that mimic protective insect burrows or brood rooms. Some of the Oncidiums mimic the appearance of male Centris bees in flight, hoping to incite territorial combat resulting in pollination. And then there are many orchids that hold out the promise of romance.
In one way or another, orchids have evolved reproductive strategies that play on an animal's three most urgent needs: for food, for shelter, for sex. Has the plant world produced any more brilliant students of animals' desire? I doubt it. Orchids are nature's meta-flowers, improvising on what has come before. For orchid deception can only succeed in a world where most things in nature really are what they seem: where flowers really do offer nectar and where they don't dress up as insects.
The orchids' baroque pollination strategies raise challenging questions for the evolutionist, however. Since natural selection seldom rewards unnecessary complication, why haven't orchids stuck with more straightforward pollination strategies based on nectar reward? And how in the world did their sexual practices become so elaborate? As for the hoodwinked pollinators, what, if anything, do they gain from their relationship with these flowers? If the answer is "nothing but frustration", then why wouldn't natural selection eventually weed out insects so foolhardy as to spend their time mating with nature's version of the inflatable love doll? Many of these deceptions are so specific they fool only a single pollinator and, as for the Ophrys, they don't work all that often. So what possible advantages could there be in depending so absolutely on a single pollinator, and one you can't even count on fooling all the time?
Botanists and evolutionary biologists have come up with fascinating answers to all these questions: indeed, the peculiarities of orchid sex offer one of the great case studies of natural selection, as Darwin himself understood. Darwin was fascinated by orchid pollination strategies, and, though he was puzzled by the purpose of Ophrys orchids' uncanny resemblance to bees (pseudocopulation wasn't observed until 1916), he taught us much of what we know about these plants in The Various Contrivances by Which Orchids Are Fertilised by Insects, the volume he published immediately after The Origin of Species. Indeed, some scientists believe that had he published his orchid book first, the theory of natural selection might have encountered considerably less scepticism than it did. Why? Because Darwin painstakingly demonstrated how even the most improbable features of these flowers serve a reproductive function. Many of their structures are so perfectly adapted, both to the plants' requirements and the morphology of their pollinators, that they offered Darwin elegant proofs of his outlandish theory.
More recently, biologists have developed theories to explain why some orchids have evolved away from a simple nectar reward for their pollinators. John Alcock, an evolutionary biologist and author of An Enthusiasm for Orchids, proposes two intriguing explanations. When botanists experimented by adding a nectar reward to a normally nectarless orchid, they found that the pollinators hung around longer, happily visiting other blooms on the same and nearby plants. This does not suit the orchid's interests, however, since inbreeding results in lower-quality seeds. As with the bee orchid, pollinator frustration works to the advantage of the plant, since the insect is apt to leave quickly and travel further. Other studies suggest that a thwarted pollinator will thrust himself more deeply into a flower and thrash about in search of promised food, improving the odds that he'll crash into the pollinia and then leave in a huff.
There may also be benefits to developing a relationship with a single, highly devoted pollinator. Nectar, beloved by so many different animals, attracts all sorts of riffraff that may not deliver your pollen to the right target. But if instead you produce a scent that attracts only the males of one species of bee, then you can ensure that your pollen will end up precisely where you want it: on the stigma of a far-flung orchid of your own kind.
The exactitude of the perfume business may also help explain the astounding biodiversity of the orchid family. A mutation producing even a slight change in an orchid's scent could, strictly by chance, turn out to be the key that unlocks the sexual attentions of a new pollinator, while at the same time completely turning off the original pollinator. This can function much as geographic isolation does in the creation of new species: by preventing new mutant flowers from being pollinated by older ones. The novel orchid can evolve in genetic isolation from its forebears – a prerequisite for creating a new species.
Orchids excel at spinning off new species. In fact, one of the curiosities of the orchid family is the fact that there are so very many species and yet relatively few orchid plants – remarkably little biomass, compared with other important plant families. Yet the orchids' small numbers ensure their survival. If deceptive orchids were more common, their ruses would no longer work, since they depend on the ubiquity of honest flowers.
There is one more characteristic of orchids that helps explain their extraordinary diversity of form as well as the ingenuity of their pollination strategies. Flowers, in general, come in two types: the radial symmetry of the daisy or sunflower, or the bilateral symmetry of the lily or orchid. The second way of structuring a flower is more complex and therefore offers many more possibilities for variation. It also opens up the possibility of mimicking the morphology of your pollinator, since the symmetry of all the higher animals is also bilateral.
To learn all this about orchids is to admire them more but perhaps love them less. And to wonder if we too haven't fallen prey to their deceptive charms. The very name of the orchid comes from the Greek word for testicle, referring not to the plant's flowers but its bulbs, organs that have long been endowed with aphrodisiac properties. But it doesn't take a Freudian to discern a strong sexual subtext in the passion for these flowers, especially among men, who, as any visit to an orchid show will tell you, suffer disproportionately from "orchidelirium" – the Victorians' term for the madness these flowers inspire.
Is it possible that humans can look at an orchid and, like the deluded orchid bees, see an apparition of female anatomy? (Georgia O'Keeffe certainly did.) Could it be that plant sex and animal sex have got their wires crossed in human brains, just as they have in insect brains? Ever since the first human-hybridised orchid bloomed (the earliest in the Western world was recorded in 1856), we humans have become important orchid pollinators, lured into advancing the orchid's interests, assisting it in its quest for world domination. Today, there are some 100,000 registered hybrid orchids, most of them literally inconceivable without us.
Not that any of this was ever in the orchid's plan. In evolution there is no plan, of course, only blind chance. But what are the chances that a flower deemed sexy by a handful of witless insects would also be so deemed by us? Let's face it: we're all orchid dupes now.
From Pollan's book: Botany of Desire
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