Horse chestnut, conker

The morning after last week’s storms, our morning walk was littered with ‘conkers’, the large and shiny seeds of the Horse Chesnut (Aesculus hippocastanum). Ryan started picking some of the nicer ones up. “The people at work”, he said, “have been discussing whether or not conkers repel spiders. I’m going to try it.”

The idea that conkers repel spiders is a long-standing one, with strong proponents on either side of the debate. As a scientist I had a ton of questions about how it would work, none of which can be answered because there’s not a scrap of proof that it does work – only anecdotal evidence. (They can, however, repel clothes moths.)

Ryan spread his conkers out in the downstairs toilet, the smallest and most spider-infested room in the house. There are one or two sitting on every available flat surface:

Conkers on the toilet cistern

This morning, as we were walking, Ryan told me that the spiders were definitely leaving the downstairs toilet.

I beg to differ:


There are at least four spiders in there. I suspect that – if indeed there has been a reduction in the spider population – they have just taken to eating each other.


One of the first memories I have of this house (and garden) is of a squirrel scarpering over the fence with a horse chestnut. I assume it had buried it in the garden at some point, and was retrieving it. We’re a bit too far from the local trees for their seeds to arrive by themselves. Last week the squirrels were beside themselves, rushing to collect the fallen seeds. I think they must have reached ‘peak chestnut’ for the moment, as they’ve calmed down.

Horse chestnut trees are a much-loved part of the British landscape, but they’re not a native species. They were introduced (from Turkey) in the 1600s, for their ornamental value. They’re found in parks and churchyards, large gardens and along some streets. They’re one of the few trees Brits can recognise with ease, although admitting to playing conkers at school is now admitting to being ‘of a certain age’. Since the advent of mobile devices, playing conkers has become a thing of the past, to the point where the word has been removed from children’s dictionaries. There’s a lovely story in the Independent from a few years ago, how the horse chestnut conkered Britain, in which the author brings home horse chestnut seeds from France for his kids. It brings to mind Michael Pollan’s Botany of Desire, which proposes that the most successful species on Earth are the ones that have persuaded humans to help them propagate.

The 400-year reign of the British conker could well be coming to an end, though. The trees are ravaged by pests and diseases, and may not survive much longer. Our local trees, venerable old specimens, lose their leaves much earlier, and there are far fewer conkers than I would expect.

Horse chestnut, conker

I’ve just been reading Feral by George Monbiot, which is an impassioned (and extremely controversial) plea to rewild some areas of the UK, by allowing them to chart their own course, rather than trying to ‘conserve’ them in a particular state (which will become increasingly difficult as the climate changes, anyway). Monbiot’s view is very animal-centric. He talks about native trees and bushes being allowed (or actively encouraged) to take over the landscape once more, to provide an environment in which species that have become extinct (some quite recently) can be reestablished. Animals such as wild boar, lynx, beavers, elk and even wolves. He has done a lot of research, both into the ecology of trophic cascades (the unexpected, and extremely complex, effects on the ecosystem of re-introducing top-level predators) and the economic costs and benefits of allowing parts of the country to re-wild. He points out that Britain and Ireland are far behind our European counterparts on this topic, refusing (for the most part) to give it a chance.

For Monbiot, rewilding the landscape will give us back something we’re missing, the thrill of a complex and healthy ecosystem, which includes occasional glimpses of animals and birds we’ve long-since forgotten, but for which he suspects we carry some sort of ancestral memory or genetic need. Personally, I would love to see elk roaming British forests once more; but for that to happen we first have to let the forests regrow! We have to rediscover, and value, the benefits that trees can bring us. From mental wellbeing to flood protection to… they’re almost endless, really.

But we live in an age where protests against tree felling in Sheffield aren’t making much headway, and ancient mulberry in London is threatened by a housing development. Although there’s plenty of science to show that green spaces and trees benefit our health and the economy, it seems that message hasn’t really sunk in yet.

Which is why it’s important to support trees where we can, and one simple way to do that is to vote for your favourite for Tree of the Year. There are no horse chestnuts on the list in the English region; I’m torn between voting for another ancient mulberry in London, or a Plymouth pear.

“No one is sure whether this species is native to the UK. The Plymouth and Truro trees could be ancient local inhabitants, dating back before the English Channel appeared, or more recent immigrants whose seeds were brought here by birds.”

Given my obsession with all things Mesolithic this summer, that may just have swung my vote in the direction of the Plymouth pear. Which tree are you voting for?