Orchid flowers

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1 Introduction
2 Examples
3 Links
4 References
5 Orchid evolution
6 Pop-Sci Further reading
7 Appendix: Quotes
8 More (remotely-hosted) pics

Introduction

Orchid flowers are among of the original "complex contrivances" in biology that astounded naturalists. Their pollination mechanisms often involve Rube-Goldberg like complexity. For example in some orchids the bee flies in, tries to land, falls into a fluid-filled bucket, is only allowed to escape by crawling up a single passageway, which has a trigger that slaps pollen bags onto the bee's back, after which it is allowed to fly to another flower.

Orchid contrivances are really just another example of Michael Behe's "irreducible complexity." They put your average mousetrap to shame, in fact. Unfortunately for Behe, Charles Darwin was well aware of orchid complexity and of the Paleyian IC argument. The first book Darwin published after the origin of species was On the various contrivances by which British and foreign orchids are fertilised by insects.

Examples

Most species of the genus Ophrys ("eyebrow") imitate the female form of their specific pollinator, usually a bee, or a wasp, sometimes a large fly, or a beetle. This visual lure is enhanced by the production of pheromones which mimic the female sex pheromones.
The labella of Paphiopedilum species are modified into pouches. Flies or bees are lured into the pouch due to the bright colors of the flowers, and in the process of climbing out of the pouch, the hapless pollinator gets the flower's pollinium (pollen packet) glued to its back.
The bizarre Catasetum orchids produce either male or female flowers, depending on the individual. Male flowers have special triggers that literally flick away the pollinators they lure in the process of applying their pollinia. Darwin, himself, observed this spectacular process in C. saccatum, and was ridiculed by Thomas Huxley as a result due to the event's alleged preposterousness.
The Star of Bethlehem Orchid, Angraecum sesquipedale, of Madagascar, has an 18 inch long nectar-spur emanating from its labellum. Knowing that sphinxmoths pollinate all of its relatives, Darwin predicted that there was a sphinxmoth with an 18-inch long tongue that pollinates it. Over twenty years after Darwin's death, the Madagascan sphinxmoth Xanthopan morganii praedicta, which has an 18 to 20 inch-long tongue, was discovered. Paradoxically, this particular sphinxmoth has never been observed feeding on the orchid in the wild.

References

Darwin, Charles (1862). On the various contrivances by which British and foreign orchids are fertilised by insects. Online at the British Library.

Orchid evolution

I have only begun to investigate the topic in depth, but I've read several sources that go into the topic in some depth. I am sure there is much new molecular work on orchid evolution, but I haven't had a chance to look it up yet.

Pijl, Leendert van der, an Dodson, Calaway H. (1966). Orchid flowers: their pollination and evolution. Coral Gables, Fla.: Published jointly by the Fairchild Tropical Garden and the University of Miami Press. pp. 1-214.

Benzing, David H. (1987). "Major Patterns and Processes in Orchid Evolution: A Critical Synthesis." Orchid Biology: Reviews and Perspectives, Volume IV. Edited by Arditti, Joseph. Ithaca, N.Y.: Comstock Pub. Associates. pp. 33-77.

Arditti, Joseph (1992). Fundamentals of orchid biology. New York : Wiley. pp. 1-691.

This book is essentially a textbook on all aspects of orchids. Chapter 3, "Evolution," spans pp 103-134.

Pop-Sci Further reading

Dawkins, R.', 1995. River Out Of Eden. Phoenix. Ch 3 discusses the Orchid as an example of IC.

Appendix: Quotes

Stephen Jay Gould's view of orchids:

Orchids manufacture their intricate devices from the common components of ordinary flowers, parts usually fitted for very different functions. If God had designed a beautiful machine to reflect his wisdom and power, surely he would not have used a collection of parts generally fashioned for other purposes. Orchids were not made by an ideal engineer; they are jury-riged from a limited set of available components. Thus, they must have evolved from ordinary flowers.

-- "The Panda's Thumb," The Panda's Thumb, New York: W. W. Norton, 1980, p. 20. Source

How Darwin's orchid book is often forgotten:

Darwin's next book, published in 1862, was entitled On the Various Contrivances by Which British and Foreign Orchids Are Fertilised by Insects, and on the Good Effects of Intercrossing. This was a deliberate attack on the argument from design, and indeed on the notion of purpose in the world in general. Even the title was ironic, for Paley had said that there can be no contrivance without a contriver. Darwin managed to achieve two major goals. He showed how complex and remarkably effective adaptations could in fact be built up by small steps through natural selection. And he turned the argument from design on its head: Nature produces what we might call contraptions rather than contrivances. In other words, natural selection predicts both adaptation and maladaptation. The latter makes no sense as a deduction from the creative action of an omniscient and omnipotent being. Carried to its logical conclusion, the argument from design gives rise to the argument from incompetent design, hence to an argument for atheism.

The Harvard botanist Asa Gray was one of Darwin's ablest supporters, but the book on orchids was a bit much for Gray's religious sensibilities. He devised a theory that John Dewey later called design on the installment plan: God works by natural selection but includes a dose of providence by guiding variation along definite lines. Darwin replied that a deity who did that would have to foresee everything in evolutionary history, leading to a very heterodox theology.

All this ought to be common knowledge, but it is not. Special creation - the watchmaker's work -was decisively refuted over a century ago, and evolution soon became as well established as the circulation of the blood. But people keep reinventing the same old arguments, sometimes with minor variations. Richard Dawkins is no exception. He never mentions Darwin's book on orchids.

-- Michael Ghilsen (1986). "We are all contraptions [review of Blind Watchmaker]. December 14, 1986, Sunday, Late City Final Edition Section 7; Page 18, Column 2; Book Review Desk. Source.