Stunning leaf colour and conkers make horse chestnut trees the very essence of autumn. But these beautifully boughed trees have something to offer all year

What would autumn be without the horse chestnut tree, with its famous seed, the conker, being gathered by children across the land for schoolyard games, and its handlike leaves turning golden browns and reds before gently falling to the ground, quivering from side to side as they descend as if waving goodbye to the end of the summer?

It’s a rhetorical question. But the horse chestnut, or conker tree, is not just a tree for autumn, because this icon of the British landscape has something to offer in every season, from its distinctive leaves and pretty flower clusters to its seeds that have a myriad of uses.

One of the great things it has going for it is that they’re an easy tree for children to connect with

However, it hasn't always been here. Horse chestnuts (Aesculus hippocastanum) were widely planted after being introduced to Britain from Turkey in the late 16th Century, rapidly becoming naturalised in the UK. Today these trees are a common sight in many landscaped parks, gardens, streets and village greens.

According to Pauline Buchanan Black, director general of The Tree Council, children grow fond of the horse chestnut from an early age.

“One of the great things it has going for it is that its an easy tree for children to connect with because of the seeds, using them to play conkers or stringing them together into necklaces. There are lots of different things that can be done in terms of art and science, even just watching the germination of a conker.

“It is actually a good access point for children to think about trees and how to grow them,” she says.

Conkers are the hard mahogany-brown seeds that sit inside a spiky protective casing, which drop to the ground in autumn and as many a child will tell you, this time of year is all about waging war with these ‘big guns’ on the schoolyard battlefield in a game of conkers.

And that’s what many combatants will be doing on the 11th October at the World Conker Championships in Southwick, near Oundle, Northamptonshire. The annual contest has been held since 1965 when it was conceived on Ashton village green, moving to the bigger venue due to its popularity.

It’s a much older tradition than this, with the first recorded game of conkers believed to have taken place on the Isle of Wight in 1848. Originally it was played with snail (conch) shells and then cobnuts, eventually being replaced with horse chestnut seeds by the 20th century.

If you don’t know the rules, they are quite simple. The conker is threaded onto a lace, with each player taking turns to strike the others until one gets smashed or destroyed.

Conker conundrum

Despite all the fun to be had with the seeds of a horse chestnut tree, they do have a more serious side. Conkers can be mildly poisonous to many animals, causing sickness if eaten, although some animals can safely consume them, most notably deer and wild boar.

While it may not come as a surprise, considering the name of the tree they come from, conkers have been fed to horses as a stimulant, to make their coat shine and as a remedy for coughs, and also made into food for both horses and cattle.

“People think it’s called the horse chestnut because people think horses like to eat the chestnuts, but it’s not, because they can be poisonous.

“It’s not a good tree necessarily if there is livestock around,” Ms Buchanan Black tells BBC Earth.

What makes conkers toxic to many animals are chemicals called glycosides and saponins. Deer, however, are able to break these down. These substances could potentially act as insect repellents and, rumour has it, keep spiders at bay when placed in strategic locations around the home.

Conkers are very rich in starch but due to their toxicity are unfit for human consumption, but we do use extracts in shampoos and body washes.

A tree for all seasons

Horse chestnut trees are much more than just conkers in autumn. The distinctive palmate leaves turn to a stunning orange colour through to deep red before they fall, contributing to the colour change spectacle that sweeps the country at this time of year.

And after the leaf stalks have fallen there is a scar on the twig which resembles an inverted horse shoe with what looks like nail holes – another association with horses.

Then we get these gorgeous brown nuts inside that spikey case that looks like a weapon of war

During spring, the clusters of pretty white or pink flowers brighten the trees like street lamps. But more than lighting the way they are a rich source of nectar and pollen for insects, while moth caterpillars found on the trees provide food for birds such as blue tits.

There are many things to love about horse chestnuts says Ms Buchanan Black, “One [reason] is the beautiful spreading nature of the tree and the shade that it gives, the beautiful flowers that you get and a leaf structure that is quite unlike most other deciduous broadleaf trees in the country.

“Then we get these gorgeous brown nuts inside that spikey case that look like a weapon of war,” she adds.

Uncertain future

A national inventory estimated there to be approximately half a million horse chestnut trees in Great Britain, whether they all live up to their potential height of 30 metres and 300 years old is currently difficult to predict.

The problem for horse chestnut trees, explains Ms Buchanan Black, is that it is beset by an awful lot of diseases at the moment.

The particular one that everyone knows about, and is threatening large numbers of trees, is the leaf mining moth, whose larvae feed on the trees’ leaves. And the amount the leaf miner is affecting them is quite significant.

“It starts off in the full flush of spring with loads of leaves and those lovely conical flower bracts and very quickly starts to fall prey to the leaf miner and the leaves turn brown, crumble and fall off,” says Buchanan Black.

But that’s not the only thing these trees have going against them at the moment. The bacterial infection bleeding canker occurs when a tree is weakened by the leaf miner and then becomes infected with these bacteria, which can be fatal.

There is also leaf blotch and wood rotting fungi, as well as the horse chestnut scale insect.

“One of the most worrying things is that such an iconic tree is looking so unhappy.”

They are trees that people can relate to, because it’s been a presence in their lives since childhood

But as Ms Buchanan Black concludes, “They are trees that people can relate to, because it’s been a presence in their lives since childhood. Through the game of conkers, through the wonderful big tree that stands out in the landscape and through the lovely flowers and the slightly mad seeds.”

Find out more about the work of The Tree Council during Seed Gathering Season and the upcoming 40th anniversary of National Tree Week.

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