The great tradition of flower painting in western art seems to have ended more than a century ago, in a series of tremendous bangs amid an obbligato of whimpers. Bang number one has to be the explosion of Van Gogh ‘Sunflowers’, 11 paintings in all, probably. The first four, studies of drying sunflower heads, were painted in Paris in 1887. Of the seven he painted in Arles a year later, the first were intended as decorative panels for the house he shared with Gauguin. He wrote to Theo Van Gogh: “If I carry out the plan, there will be a dozen panels ... a symphony in blue and yellow.” The decorative purpose of the panels explains their shallowness of field, simplicity of composition and brushwork. He tried to paint each one in a single day, before the processes of decay overtook the flower forms, but they withered even as he gazed on them. Like all great still life, Van Gogh’s ‘Sunflowers’ are images of the transitoriness of beauty, as shifting as sunlight itself.

Probably because they are apparently unchallenging, the Arles paintings have become art monsters. Anyone who can name a single painting can name Van Gogh’s ‘Sunflowers’. Among the whimpers is the painting of Irises in the garden at Saint-Paul de Mausole made by Van Gogh soon after his arrival at the asylum. He called it a study, which is about right; it was his brother the dealer who decided to present it as a finished work. When Australian speculator Alan Bond bid $54m for Irises at Sotheby's New York in 1987, it was the highest price ever paid at auction for a painting.

The other great bang has got to be the 250 paintings made by Monet of water lilies in the garden at Giverny, any one of which these days seems to be worth as much as a Van Gogh sunflower painting. I could, should, and probably would include as bangs the close-ups of flower faces painted by Georgia O’Keeffe — if I liked them. As I find them garish, insensitive and far less interesting than her contemplative landscape painting, at the risk of receiving hate mail, I shall class them among the whimpers. I think there are more than a few whimpers among Monet’s ‘Nympheas’, come to that.

Despite the phenomenal marketability of flower paintings, no one does them any more. What proliferates instead is botanical art. Flower portraiture is not of itself contemptible; the greatest Dutch flower painters were aware that the flowers they were depicting were worth more than their depictions, and treated them with a special awe and excitement, but they were never unaware of their fragility. Often they included moths, spiders, snails and caterpillars, as agents of destruction, but mostly they didn’t have to. The light as it fell on the carefully displayed blooms, usually against a closed, dark background, the fallen leaves and calyces on the cold stone support, the occasional munched or torn petal, all insisted that the destiny of every flower is to be pollinated, impregnated, to fall and rot.

As interest in flower-painting declines, interest in botanical art burgeons. In April, the Shirley Sherwood Gallery of Botanical Art was opened at Kew, in the belief that the general public will flock to see the kinds of plant portraits that have hitherto been immured in Kew’s study collection. Hundreds of books published every year promise to teach people how to draw plants. The emphasis is all on illustration, not on picture-making. Scientific accuracy was an aim for Breughel, Bosschaert and Savery as it was not for Van Gogh and Monet, but as such it did not militate against a concern for compositional values. Modern botanical art, characteristically, appears unaware of a picture frame, the specimen portrait floats in nothingness, ready to be cropped or reduced at the whim of a designer. All emotion ebbs away, to leave nothing but detail.

Flowers have movement and habit. We recognise a wildflower in the distance not because we can count the number of anthers, but because of the way it dances. Its stem has pliability or stiffness as well as colour and dimension. The difference between botanical art and flower-painting is the difference between the illustration in your field guide and the bird on the wing.

We can hardly forget that alongside the plant portraits made by the illustrators who accompanied the plant-hunters were the corpses of the plants pressed flat between sheets of paper.

The illustrated flower is petrified and charactered, the painted flower, whether by Seghers, Van Huysum or Ruysch, is alive and dying. If what you want is to identify a plant, botanical illustration is more useful than photography. If you are trying to grasp the nature of a particular plant, paintings — even as apparently offhand as Matisse’s ‘Pansies’ or Bonnard’s Anemones — will serve you better.

Fantin-Latour, who hated having to paint flower-pieces for a living, is said to have studied every bloom as a unique individual, another thing botanical illustration cannot do. Now that so many irreplaceable species on this small planet are threatened with extinction, elegiac portraiture of the natural world is something we need desperately to revive.

The Guardian