THERESA THOMPSON visits Amazing Rare Things at Buckingham Palace, with its echoes of the Ashmolean Museum

The world of insects, flowers, vegetables, shells, birds and animals, plus a dragon or two - as seen through the eyes of early naturalists and artists - is on view at the Queen's Gallery, Buckingham Palace. Amazing Rare Things: The Art of Natural History in the Age of Discovery features 90 artworks of incomparable quality from the mid-15th to the early 18th centuries to show how artists and collectors helped shape our knowledge of the world.

It covers a period when a spirit of scientific enquiry was taking hold in Europe, new lands discovered and new species in ever increasing numbers. Botanical specimens flooded in, embellishing the gardens of scholars and collectors and firing enthusiasms for the study of nature.

The naturalist and broadcaster Sir David Attenborough collaborated with Royal Collection curators to select works from five artists and one collector: Leonardo da Vinci, Alexander Marshal, Maria Sibylla Merian, Mark Catesby, Wenceslaus Hollar, and the Italian antiquarian Cassiano dal Pozzo.

"There is a common denominator that links all these artists," said Attenborough. "It is the profound joy that all feel who observe the natural world with a sustained and devoted intensity." In the 15th century Leonardo da Vinci's profound curiosity about the natural world led to some extraordinary drawings. Combining the observation skills of an artist with the analytical drive of a scientist, Leonardo made detailed studies of, for example, among his 18 works on show, blackberries, seed heads, Job's tears (a grass), stratified rock, and the anatomy of a bear's foot.

The exquisite Star of Bethlehem, wood anemone and sun spurge c1505-10, one of several plant studies for the foreground of a painting of Leda and the swan, reveals an interest in the structure of individual species that went far beyond what was necessary for a painting.

In Leonardo's day many people, scientists included, believed in dragons. Two are here. One is snuck in among a drawing of cats and lions, Leonardo embodying observed feline qualities into a dragon figure; the same qualities reappear in a drawing made a year or two later, c1517-18, with the curvy writhing creature in the corner of Horses, St George and the Dragon, and a lion.

Curvy shapes also figure in the work of Maria Sibylla Merian (1647-1717). Fascinated from childhood by the life cycles of butterflies, Merian journeyed at the age of 52 to Suriname (Dutch Guiana) in South America to study the indigenous flora and fauna in their tropical habitat. She returned two years later to work on The Metamorphoses of the Insects of Surinam (1705), a lavishly illustrated book that is one of the most important works of natural history of its era. She intended it to appeal to non-specialists as well as the scientific community, however, dedicating it both to "lovers of art" and "lovers of insects".

The desire to shape a thing of beauty was at times at odds with accuracy. In her glorious hand-coloured plates we see some of the precision expected of a scientific illustrator, but also the artistic sensibilities a woman beguiled by curves, coils and loops. Composition mattered above all; relative sizes, unlikely juxtapositions or behaviours less. Merian's snakes are pleasingly arranged in colourful whorls, caterpillars are half the size of snakes, leaf-cutter ants go about their job wrongly (according to Attenborough) and a giant spider eats a hummingbird (also wrong).

The eminent collector Cassiano dal Pozzo (1583-1657) emphasised the importance of direct visual observation when commissioning artists to record plants, birds and animals for his museo cartaceo (Paper Museum'). He assembled thousands of drawings and prints in the process of making a visual encyclopaedia that attempted to classify the natural and man-made' worlds, including the extraordinary Maned three-toed sloth and Deformed Broccoli on show here.

Many of the species portrayed in this exhibition were once the amazing rare things' of the title; others were more common or garden. And some are now extinct or have been brought close to it.

The passenger pigeon is an example. Painted c1722-6 by the celebrated English naturalist Mark Catesby, who compiled the first comprehensive survey of the flora and fauna of the then British colonies, the bird once flew in many million-strong flocks over North America; it was extinct by 1914. And the American Bison, in Catesby's day ranging over a third of the continent, was near extinction by the end of the 19th century. Back home in the English garden we find one of the most extraordinary botanical artists of his time: Alexander Marshal (c1620-1682) and his beautiful florilegium' (flower book), a work unique in English 17th-century art. Marshal devoted 30 years to recording the contents of English gardens over the course of a year, from the crocuses and primroses of spring, to roses, anemones, and autumnal gourds.

Marshal painted purely for his own pleasure and for study with his friends, a circle of leading gardeners and collectors who exchanged and traded in botanical specimens, among them John Tradescant the Younger. We can presume Marshal painted Tulips in Tradescant's garden at Lambeth for it shows a variety (Tulipa gesneriana) grown there in 1656; the earliest record of Marshal's life dating from 1641 shows he stayed at his house. Marshal also painted the double-flowered pomegranate, introduced to England around 1620 by his friend's father, John Tradescant the Elder, who began the collection of amazing rare things' that later became the basis of the Ashmolean Museum.

The exhibition at The Queen's Gallery, Buckingham Palace, is on until September 28 and is open daily 10am-5.30pm. Tickets and further information from www.royalcollection.org.uk or 020 7766 7301. (a booking fee applies).