Outsider art: in praise of botanical paintings and illustrations

Botanical art shows plants in more vivid and stunning detail than a photograph ever could, argues our green-fingered correspondent

Not long ago, I accompanied a small group of American enthusiasts on a tour of some Italian gardens round Florence and Siena. As part of the package, I arranged for us to have access to a particular set of flower paintings in the Gabinetto Disegni e Stampe at the Uffizi, which are not normally on show. As it happened, the Uffizi was on strike the day we were to go, but the director sent a message that he'd meet us at a side door and let us in.

And so, quite early in the morning, our little gang trooped through the silent, empty corridors of the Uffizi to the magnificent Gabinetto, where, like a world-class conjuror, the director produced sheet after sheet of the work commissioned by the Medici from the artist, Jacopo Ligozzi: iris, anemone, foxglove, spurge, gentian, thrift, valerian, a magnificent double red peony, angelica, mandrake, branches of plums and figs, agave, marvel of Peru, a pineapple, a red-flowered morning glory with foliage as fine as lace.

The watercolours were made between 1577-1587, but here were Ligozzi's flowers, as life-like as the day they were picked, essential characteristics carefully captured on each speckled, slightly-foxed image. On the agave, he'd caught with extraordinary precision the ghost image that one leaf presses on the one inside it, a feature of the plant that still transfixes me today.

Francisco I of the Medici brought the great Italian naturalist, Ulisse Aldrovandi, to see Ligozzi's paintings. "They lack nothing but the breath of life itself," he remarked. And it's true. Nobody in our little troupe said a word. They just gaped. For me, their silence was more telling than words. I hope the director of the Gabinetto felt the same.

That ability to capture the essential nature of a plant lies at the heart of all the best botanical art. It's celebrated in two new books – The Golden Age of Flowers by Celia Fisher (British Library, £14.99) and The Golden Age of Botanical Art by Martyn Rix (Andre Deutsch, £25). Using images from some of the most celebrated botanical works in the British Library, Fisher arranges a vivid alphabet of flowers. She starts with an alstroemeria by the great French artist Redoute (his Les Liliacees was first published in Paris at the beginning of the 19th century) and finishes with zinnias, which arrived in Europe from Mexico in 1753.

Rix's book ranges more widely and uses 250 images from the fine library at Kew. Ligozzi is in it. So, of course is Redoute, perhaps the best-known flower painter ever. Using the collection of roses built up by the Empress Josephine at Malmaison, he started his huge project of painting them, publishing the first set of images in 1817. Hotel chains buy reproductions of his prints by the thousand: bedrooms, bathrooms, passages, bars will all have fading copies of the miraculous originals. Rix tells the full story of the famous rose book, for which Redoute, ironically, couldn't find a backer.

The Golden Age is arranged as a series of stories, told in chronological order. It's like a tasting menu – covering delicacies from the 13th century BC (a fabulous Minoan vase decorated with palm trees) right up to the present day. You might have thought that the arrival of the camera, the quick click of the iPhone, would make botanical painting redundant. But it hasn't. Not at all. The final image in Rix's book is Ann Farrer's modern and minutely-observed study of a bamboo (Phyllostachys heteroclada), the upright stems and angular foliage making an image of abstract beauty as well as botanical accuracy.

Important characteristics of a plant can be subtly brought out in a botanical painting: the way a leaf sheath curves round a stem, the way foliage is veined, the way the pollen is held on a stamen. A photograph works differently, giving all characteristics equal value. And a single painted image can contain extra details of seed pods, autumn colouring and other seasonal effects that a photograph, even one that has been well Photoshopped, cannot do so clearly.

A new show that opens tomorrow at Chatsworth sets the work of practising artist Emma Tennant very firmly in this long, unbroken tradition of botanical painting. At the heart of the show are images of the plants and flowers that are special to Chatsworth – the beautiful orchid Coelogyne cristata sent back from India in 1835 by a young Chatsworth gardener, John Gibson, and the Cavendish banana, the forerunner of the ones we eat today, grown at Chatsworth by their famous head gardener, Joseph Paxton. He planted it in 1835 and the following year, picked a hundred fruit from it.

Paxton's story is told in the superbly researched catalogue that Emma Tennant has written to set her paintings in context. Nobody, though, has ever been able to better Paxton's own account of his first arrival at the great Derbyshire seat of the Duke of Devonshire. "I left London by the Comet Coach for Chesterfield; and arrived at Chatsworth by half-past four o'clock in the morning of the ninth of May, 1826. As no person was to be seen at that early hour, I got over the greenhouse gate by the old covered way, explored the pleasure grounds and looked round the outside of the house. I then went down to the kitchen gardens, scaled the outside wall and saw the whole of the place, set the men to work there at six o'clock, then returned to Chatsworth and got Thomas Weldon to play me the water works and afterwards went to breakfast with poor dear Mrs Gregory and her niece, the latter fell in love with me and I with her, and this completed my first morning's work at Chatsworth before nine o'clock."

The breakneck pace continued throughout Paxton's career and Emma Tennant's atmospheric watercolours capture many of the new plants that he and his employer, the sixth Duke, brought to Chatsworth. One of them, the wintersweet (Chimonanthus praecox) still grows on the Conservative Wall, the long series of glass cases that runs from the orangery at Chatsworth to the stables. We now know that wintersweet is perfectly hardy and doesn't need the protection of glass, but all these things had to be found out by trial and error. Paxton didn't do error.

Scattered through the show are some older images of the plants that Emma Tennant has painted, all from the Chatsworth picture collection. Particularly touching are a pair of paintings of a broad bean plant, the Tennant version in black and white flower, the other (possibly by the 16th-century artist Giovanni da Udine) in full fat pod.

The exhibition Emma Tennant at Chatsworth opens tomorrow in the New Gallery at Chatsworth, Bakewell, Derbyshire DE45 1PP and continues until 30 June (11am-5.30pm). Entry to the show is included with admission to the house and garden (£16)