Why Britain has grown to love the spreading chestnut

There is much more to the horse chestnut tree than conkers. Its flowering is one of the most spectacular sights of the spring.

The broad leaves spread out in a brilliant iridescent green and above them open the the tall, upright, white or pink "Roman candles", the biggest blossoms of any British tree.

They are so splendid in that flowering time, lasting a fortnight, that they are among Britain's most beloved trees, but they are not native. The natural home of Aesculus hippocastanum is south-eastern Europe, the Balkans and Turkey, where it grows in rocky landscapes very different from the parks and avenues of Britain.

The first trees were planted here in the early 17th century by John Tradescant the Elder, an Elizabethan gardener and botanist, and they soon became a regular ornamental feature in the gardens of stately homes across the country. The name originates from the practice of adding the fruits, conkers, to horses' feed, although the tree is not related to the rather similar-looking sweet chestnut, Castanea sativa, which produces the things we eat from winter braziers and add to turkey stuffing.

The horse chestnut's hard, glossy brown (but inedible) fruits were themselves not named until the 19th century, when they replaced cobnuts and snail shells in the already popular game of conkers.

The tree's weak wood is not particularly valuable. Its limited uses include making trays for fruit, toys and, until recently, artificial limbs, because it is so light and easily shaped.

However, extracts from the tree are a common ingredient in shampoos, because their ability to stimulate surface blood vessels helps make hair healthy.

For the same reason, they are often added to bubble baths, and have been known to help varicose veins. What is more, in an accidental discovery, conkers left to ferment on a windowsill eventually led to the development of sunscreen.

But the tree's most interesting contribution to history came during the First World War, when scientists developed a way of using conkers to manufacture a crucial component of the cordite which was used as a propellant in British shells.

In the autumn of 1917, schoolchildren from Britain collected 30,000 tons of conkers, managing to replace the supplies of corn (previously used in cordite manufacture) from Canada which had been cut off by the German submarine blockade, thus rescuing the British war effort.