Tree of the month: June 2024 - Horse Chestnut

The Horse Chestnut was introduced to England in the 16th century from Türkiye and became very popular for avenues and specimen trees in Stately Homes and urban parks from the 17th century. It was especially valued for its decorative flowers, commonly known as ‘candles’. The fruits have long been popular with children playing the game ‘conkers’. There are nearly half a million in Great Britain and Capability Brown planted 4,800 on just one estate in Wiltshire. Horse Chestnut trees can grow to a height of 40 metres and live for 300 years. The tree grows rapidly and in a range of soils. There is a decorative pink flowered cultivar often grown in parks.

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​‘Sticky buds’, ‘palmate’ leaves (like the spread fingers on a hand), ’candle’ flower spikes and conkers are all easy ways to identify Horse Chestnut trees through the seasons. In winter the way branches upturn at their ends also helps.

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​Wildlife value of Horse Chestnut: While this tree doesn’t support as much wildlife as many native species its rich supplies of pollen and nectar do support insects, especially Bees. The caterpillars of some moths, like the Triangle Moth, feed on the leaves and deer can eat the conkers. When mature the tree provides shelter and nest sites for some birds, including Woodpeckers.

A bleeding canker is sadly now affecting the trunks of some mature trees and since 2002 many of our UK trees have become blighted in autumn by the numerous larvae of the Chestnut Leaf-Miner Moth. These larvae affect the leaves in high numbers, are unsightly and may weaken the tree over time but Blue Tits, Goldfinch, Robins and other birds are learning to feed on them- an autumn boost for an increasing number of our birds.

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​The relationship between Bees and Horse Chestnut flowers: Young flowers have a blotch of yellow- a ‘bee guide’ that directs bees to the rich nectar source at the neck of each flower. Once the flowers have been successfully pollinated the bee guide becomes deep pink. The loss of the yellow guide signals to the bee that nectar production in that flower has ceased, it doesn’t waste its energy trying to feed at empty flowers and turns to those flowers still showing the yellow patch. The Horse Chestnut benefits by increasing the chance of cross-pollination which makes the seed and then the tree more resilient.

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​Did you know? Bees don’t see colour, and particularly red, the way we do. Research is ongoing as to how they see it - maybe when in contrast to green, but in general they aren’t so attracted to red flowers.

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​Human uses of Horse Chestnut: Conkers have been used as cattle feed when other foods were scarce and in Turkey, where Horse Chestnut trees are indigenous, conkers were fed to horses to treat various medical conditions and to cure their wind. Leaf extracts have been used to treat bruises and strains in people - they contain the anti-inflammatory chemical aescin. It is still in use as a herbal remedy.

There are Victorian recipes for conkers ground into flour but it is mildly toxic in large quantities and needed to be leached to reduce the bitterness.

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​One of the Soapberry family, the Horse Chestnut contains saponins - just scrunch up the leaves in water and see the foamy results - a simple way to wash if you are out in the wilds! Horse Chestnut is still added to cosmetics and shampoos and halved conkers are being used by some as a natural washing agent in washing machines (look online for the technique). Due to its gentle soapy qualities Horse Chestnut was used to wash delicate fabrics like tapestries.

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​The timber is creamy-brown and, being weak, has few uses except for carving. However, until the recent development of manufactured materials, being both light-weight and easy to shape it was used to make artificial limbs. Being absorbent, the wood was also used in the past to hold stored fruit. In 1917 children were offered money by the Ministry of Supply to collect conkers for “the war effort” but the reason was kept a secret. It was later revealed that it was hoped to use the starch in the conkers to produce acetone to supplement a shortage of cordite. In the end it proved too heavy to transport the huge quantities needed.

Myth: the longheld belief that conkers brought into the house in autumn would keep spiders away has unfortunately been found to be ineffective.

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​Playing conkers: Before our version of conkers, a name derived from ‘conquerors’ or ‘conquer- to knock out’. the game was being played with snailshells and hazel nuts. This is recorded by Robert Southey in his memoirs of 1821. The first record of it being played with conkers is in 1848 from the Isle of Wight. The World Conker Championships, held annually in October in Ashton, Northamptonshire began when a group of anglers, having to abandon their fishing trip in 1965, decided to hold a conker competition. Traditionally a string is threaded through the conker -to cheat and make the conker harder they are variously baked or soaked in vinegar. You start with a none-er and every time you win with that conker it is renamed- a one-er. two-er etc until someone else’s conker knocks it off its string.

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​The Horse Chestnut in poetry, art and history: Contrary to some press reports conkers was not banned in English schools. Michael Rosen recites his prose-poem on his school visits:
“And you Conker! Always up for a fight, aren’t you? Let me get at him, let me get at him- that’s you. Heh. Well I know your little secret: There you are, lying about in your little green house and then, when the walls are split, out you pop like you think you’re some shiny new car cruising out of the garage. But I’ve seen inside your little green house. You lie there for weeks all tucked up in a soft white bed, don’t you? Ha! Hardman! Ha!”

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​Anne Frank could see a Horse Chestnut tree from the small window in her family’s secret annex in Amsterdam, where she hid from the Nazis during World War Two. She recorded its changes through the seasons. An entry on 13th May describes her pleasure at seeing it “in full bloom”. A successful campaign prevented it being felled and, after it was blown down in a gale, saplings from the original tree were distributed around the world.

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​Extract from John Clare: My Early Home:
The red-breast from the sweetbriar bush
Drop’t down to pick the worm;
On the horse-chestnut sang the thrush.
O’er the house where I was born,
The moonlight, like a shower of pearls
Fell o’er this bower of bliss
And on the bench sat boys and girls:
My early home was this.