The two underground storage organs, one slightly larger than the other,which are necessary to European orchids for surviving dry southern summers or cold northern winters, earned them their Greek name Orchis which means testicles; together with an enduring reputation as an aphrodisiac. In 1597 John Gerard classified orchids as either dogs, goats, fox, hares or fools stones, although he distanced himself from those apothecaries who prescribed them "to stir up lust". This practice nevertheless travelled to the New World as it was colonised. In 1672 John Josselyn recorded seeing a woman collecting orchids in New England: "I once took notice of a wanton woman compounding of the solid roots of this plant with wine - which wrought the desired effect" (how come he knew?) In the days of tea houses and coffee shops there was also sold an invigorating gruel made of orchid roots and called saloop, from an Arabic name which meant (yet again) testicles. In ancient China it was mainly the heady scent of orchids, especially Cymbidiums and Dendrobiums, which linked them with a reputation for sexuality. Confucius referred to the orchid as king of fragrant plants and the ninth century Tang poets set their love poems in a haze of orchid perfumes and incense. Orchids actually are the most promiscuous of plants, hybridising far more readily than most, employing extremes of colour, beauty and diversity, and deceiving male insects with the appearance and smell of females into acts of pseudo-copulation which, by transferring pollen, enable the orchids to fertilise each other.

Orchids in paintings, although they are significant, are also rare. Only three appear in Italian Renaissance paintings; a Pieta by Cosimo Tura (Venice, Museo Correr) has an orchid in the foreground; equally prominent is what looks like a type of man orchid at the feet of a Virgin and Child by Gaudenzio Ferrari (Bergamo, Accademia Carrara); and in Verona (Museo di Castelvecchio) there is a painting by Girolamo dai Libri of Christ with the Samaritan Woman where an orchid is placed behind Christ. Some contemporary names of orchids showed an effort to supplant the usual sexual associations of orchids by asserting their religious symbolism. Names such as Gethsemane flower or Cross flower were linked with the legend that the early purple orchid, O. mascula , grew beneath the Cross of the Crucifixion and the leaves were spattered with the blood of Christ, hence their irregular brown stains. Similarly in Germany orchids with spotted leaves were called kreuzblumen.. Some spotted orchids, for instance O. maculata, have roots not in two tubers but shaped more like a hand (though not necessarily with the full complement of fingers). These were generally known in English as dead mens fingers. In classical tradition they were the satyrion orchids, satyrs supposedly ate them to induce an orgiastic state, and the original Orchis was the human son of a satyr killed during a Baccanalian orgy and turned into a flower. The Church purified the old legends by renaming this group of orchids Palma Christi. The same ambivalence is apparent in the naming of lady's slipper orchids, whose English name was originally Our Lady's Slipper and therefore religious. In 1640, when John Parkinson in Theatricum Botanicum described the new arrival of a North American slipper orchid (probably Cypripedium acaule) and compared it with the European species, he called it Calceolus Mariae Americanus and wrote; "a sort there has been brought from the North parts of America, differing only in being greater both in stalks, leaves and flowers, which are not yellow but white with reddish strakes through the bellies of them". But the French called their slipper orchids sabots de Venus and the Latin names Cypripedium and Paphiopedilum are taken from classical titles of Venus linked with her birthplace and island sanctuary of Cyprus.

A fine visual example of the orchids' capacity for absorbing double meanings occurs in the Unicorn Tapestries (N.Y. Met). Made around 1500, the superb set of tapestries shows the hunt, death and resurrection of a unicorn which can be seen as an allegory of Christ, but also has definite undertones of an older fertility deity whose death and resurrection took place with the seasons. The tapestries are decorated with a great variety of fruit, trees and flowers, but one of the most symbolic plants is the purple orchid which grows silhouetted against the white flanks of the risen unicorn as it sits under a tree. Since Christian legend claimed that the leaves of O. mascula were originally spotted with Christ's blood, this provided a religious association. It is very likely that here the orchid symbolised not only resurrection in the Christian sense, but also regeneration in a more natural sense. The orchid was therefore once again building on its reputation as a fertility symbol.

At much the same time Shakespeare included orchids in the garland which Ophelia was gathering when she drowned: "Long purples that liberal shepherds give a grosser name, but our cold maids do dead men's fingers call them" (Hamlet Act IV sc. vii). Long purples is the folk name of O. mascula and the grosser name would be dog or fools stones, or a local variant such as cuckoos, meaning cuckolds. The name dead man's fingers was also applied to O. mascula, although it was more appropriate for the other spotted orchids, the satyrions, with tubers resembling decaying hands. Shakespeare therefore seemed to be condensing two very appropriate plant images of sex and death - for the lust Ophelia had aroused in Hamlet and for her drowning - in a way his audiences would have appreciated. The PreRaphaelite artist J.E. Millais, when he painted the Death of Ophelia (London, Tate Britain), assumed that Shakespeare was referring to two different orchids. One of Millais' orchids is certainly the long purple, the other is white and may be the elusive ghost orchid Epipogium aphyllum, which would be a clever and rather Victorian way of representing Shakespeare's dual meaning.

Millais was using native European orchids. But meanwhile a great deal of fresh interest had been created by the descriptions and introductions of tropical orchids from America and Asia, late in the seventeenth and early in the eighteenth centuries. In the 1820s new methods of heating glasshouses with hot water pipes (rather than hot air) produced a damp rather than a dry heat, far more congenial to tropical plants and making possible a greatly increased scale of orchid introduction, cultivation and hybridisation - nicknamed orchidomania. Among the Victorians who succumbed to this passion was Joseph Chamberlain, President of the Board of Trade in Gladstone's cabinet until they quarreled over Ireland in 1886. Cartoonists always depicted him with his monocle and an orchid in his buttonhole, usually a Cattleya, which is also what he wore for his official portrait (London, NPG). Another eminent Victorian associated with orchids was Charles Darwin. The publication of the Origin of Species in 1859 had shaken the foundations of natural history without convincing all concerned. But in 1862 Darwin published a paper on the fertilisation of orchids by insects which earned great scientific respect and paved the way for wider acceptance of his theories of evolution, and for a much expanded programme of breeding orchids. Instead of a portrait with orchids, Darwin received a comic artistic tribute from Edward Lear who, in his Nonsense Botany published in 1871, depicted Piggiwiggia pyramidalis to help immortalise Darwin's discoveries relating to the pyramid orchid (Orchis pyramidalis). Another of Darwin's pronouncements concerned Angraecum sesquipedale, a beautiful white orchid first discovered in Madagascar in 1798. This orchid holds the nectar with which to tempt insects at the base of a twelve inch nectary, a delicate white tube that seems to flutter outwards from the flower. Darwin deduced that it had evolved to be fertilised by a moth with a proboscis of equal length, which fifty years later was proved true when the moth was discovered and named Xanthopan morganii praedicta.

Marianne North was inspired by mentors such as Darwin to undertake her own intrepid pursuit of botanical discovery. Angreacum was one of many tropical orchids that she painted during her expeditions to America, Asia, Africa and Australia from 1871-1885. Her ornate but accurate oil paintings (Kew, RBG) show the exotic plants blooming in their natural habitat of thick foliage, dense heat and whirring insects. Meanwhile the extraordinarily parallel artistic career of Martin Johnson Heade turned towards orchids after his third South American journey in 1870. Over two decades he produced his series of Orchid and Humming Bird paintings, primarily featuring large pink Cattleyas visited by the vivid little birds, against backgrounds of tropical jungles with distant mountains and rivers veiled in heat, and humid atmospheric skies.

In France the orchid collecting fraternity included the Impressionist painter Gustave Caillebotte, who was affluent enough to have glasshouses at the family property of Yerres near Fontainebleau. He wrote about orchids to his friend Monet, and painted them on door panels to decorate his living room, recreating their rich colours, fantastic shapes and lush tropical growth; while at the same time giving a vivid impression of the inside of a nineteenth century glasshouse (Paris, Musee Marmottan). These glamourous new orchids reinforced the sexual allure which they had always had, and added a sense of the mysterious - both of science and of undiscovered lands - which spelled danger. The decadent beauty of Art Nouveau suited this mood wonderfully, and for the first time orchids became a dominant flower of an art movement. Lalique's enamelled jewellery, set with semi-precious stones, ivory and horn, often took the form of an orchid, especially lady's slipper (Cypripedium and Paphiopedilum); while Emile Galle's glassware incorporated orchid motifs in moody pinks and browns, embedded in marbled green vases and bowls. In Belgium, where Philippe Wolfers was producing the leading Art Nouveau ceramics, the sense of decadence in his orchid motifs was perhaps even more profound, especially since he favoured the skull-like blooms of Coryanthes species. These too were the choice of the Symbolist painter Johan Thorn Prikker in his disturbing painting entitled The Bride (Otterlo, Kroller Muller Mus.) The bridegroom stands in the attitude of crucifixion while the bride's shadowy gown flows through the painting and the orchid-skulls loom around them.

In the twentieth century the associations of orchids with sex and danger entered the scenarios of a number of thriller writers on both sides of the Atlantic. H.G. Wells in The Flowering of the Strange Orchid and Arthur C. Clarke in The Reluctant Orchid both imagined magnificent, predatory blossoms with an overpowering scent. More sinister still was the terrible gangster novel by James Hadley Chase, of an orchid that is never there - No Orchids for Miss Blandish - the title most likely to be remembered by anyone challenged to discuss orchids in literature. Rex Stout's Nero Wolfe, the American private detective, comes a close second, much in demand for solving insoluble crimes but doing so only in order to finance his orchid collection. Twentieth century artists were heirs to this tradition. Georgia O'Keefe in 1941 painted a white and green Rhyncholaelia (Priv. Coll.), by zooming into the centre of one enormous flower and once again hinting at the psychological reactions that orchids arouse. David Hockney set white orchids, probably Cymbidium, against the background of Mount Fuji after his return from Japan in 1971 (N.Y. Met), restoring to them an air of oriental mystery. Most recently Gary Hume's large-scale and metallic orchid paintings (Priv. Coll.) again have an ambiguous quality, as if they could be at once both sinister and pure.