15 FEBRUARY 2003, Page 35

Why is a birch-tree like a melon?

Emma Tennant

THE BOTANICAL GARDEN VOLUME L TREES AND SHRUBS, VOLUME II: PERENNIALS AND ANNUALS by Roger Phillips and Marlyn Rix Macmillan, £50 each This is the time of year for armchair gardening. The cold, dark days give one the chance to ignore the muddy plot outside and to sit by the fire with a heap of catalogues. As one reads the thrilling descriptions, next summer's garden comes to life in the mind's eye. There are no rabbits, mice, moles, whitefly or weeds to spoil the picture. Instead, the most difficult plants flourish under a sunny sky.

These two mighty tomes add up to the most inspiring catalogue I have ever read even though, unlike commercial lists, the descriptions do not exaggerate. They are strictly truthful, because they are written by Dr Martyn Rix, a distinguished botanist. The illustrations are by Roger Phillips, a painter turned photographer who uses his camera with the eye of a true artist. Rix and Phillips have been working together for 25 years and have produced 23 books, including 14 in the brilliant, best-selling Garden Plant Series. Now they have attempted a bold feat; in their own words, they aim to describe 'the genera of trees, shrubs and herbaceous plants of interest to gardeners'.

The descriptions of plants in The Botanical Garden are arranged in scientific order because, as the authors explain, they want to 'provide new information and a new way of looking at plants and gardening from a more botanical viewpoint'. Those who are familiar with the classification of plants into orders, families, genera and species will feel very much at home with this arrangement. For others, these books will provide the perfect introduction to the science of botany.

Recent discoveries, made as the result of DNA studies, are incorporated into the text. There are some surprises. Who would have guessed that the Chilean shrub azara is closely related to the violet, or that alders, birches and hazels are not, as previously thought, ancient and primitive genera, but relatively advanced, and most closely related to melons and begonias? Rix and Phillips give each genus a botanical description, followed by more information under the headings 'Key Recognition Features', 'Evolution Sz. Relationships', 'Ecology Sz Geography' and finally 'Comment'. In this way they manage to include a mass of fascinating detail.

Some of the most interesting genera are those described as monospecific because they include only one species. Such, for instance, is Ginkgo biloba, which was named by Linnaeus in 1753, about 20 years after its introduction to Europe. The gingko may be the most ancient of all living trees. Fossil leaves have been found which are 200 million years old. At that time the ginkgo grew in many parts of the world. It survived only in China, where it was a very rare wild plant, but was often planted near temples by Buddhist monks, who recognised the ginkgo as something extraordinary. Some of these temple trees are 1,000 years old, and still growing.

Another rare treasure from the forests of western China is Davidia involucrata, the so-called handkerchief tree. Its spherical flowers hacked by two large white bracts are quite unlike anything else in the plant kingdom. Davidia is named after the great French naturalist and missionary Pere Armand David, who discovered hundreds of plants and animals, including the giant panda, in the 1860s. From the other side of the world comes another monospecific genus. Saxegothaea grows in the Patagonian rain forest, and is named after Queen Victoria's consort, Prince Albert of SaxeCoburg-Gotha. History meets botany in The Botanical Garden. At the other end of the scale are genera like rhododendron, with about 800 species and thousands of hybrids, and begonia, with 1,000 species and hybrids galore. The authors obviously have had to select a few examples of these groups. Rosa and rhododendron, for instance, are each allotted six pages of photographs. Where space allows, the individual floral parts, seeds and autumn colour are illustrated, as well as the flowers and leaves. These details are shown with Phillips' usual artistry.

Some of the spreads are of breathtaking beauty. Look, for instance, at the lifesize Cyclamen repandurn and C. cilicium, complete with roots and corm, or at the twig of Kalmia latifolia, 2/3 lifesize with largerthan-life individual flowers shown below. Large plants obviously cannot be shown full-size, but I found the use of several different scales on the same page confusing, lovely as the photographs are. And the authors have been let down by the quality of printing of the colour blue. The magic ultramarine of the rare Chilean bulb Tecophilea is accurately reproduced, but other true-blue flowers like delphiniums, gentians and the Californian annual. Nemophila are shown in disappointing shades of mauve and purple. But these are minor quibbles.

At £50 each, the two volumes of The Botanical Garden are an investment. They are worth every penny. Martyn Rix and Roger Phillips have, once again, achieved an extraordinary feat of popular scholarship. I cannot imagine that any serious gardener will be without The Botanical Garden for long.