The Horse Chestnut Tree and Conkers
A Beautiful Tree
The horse chestnut is a beautiful ornamental tree with attractive leaves and flowers. It produces prickly fruit capsules which each contain a glossy brown and nut-like seed. The seed is known as a conker and has been used in a popular children's game since at least the mid-nineteenth century. The game gets its name from the seed and is known as conkers.
The scientific name of the horse chestnut tree is Aesculus hippocastanum. Despite its common name, horse chestnut isn't closely related to true chestnut trees. It's native to Southeastern Europe but is grown in parks, landscaped areas, and gardens around the world. The conkers ripen in September and October. They aren't edible and are actually toxic in their intact form. They're safe to touch, though. An extract made from horse chestnut seeds or leaves may have medicinal benefits.
There are horse chestnut trees growing in my neighbourhood in Canada. They are one of my favourite trees. The flowers are lovely to see in late spring and early summer and the conkers are fun to collect in autumn.
Features of Horse Chestnut Trees
A horse chestnut tree may grow to over a hundred feet in height. A mature tree is densely leaved in summer and is an impressive sight.
The leaves develop from sticky buds and are said to be palmately compound. This term means that a leaf consists of smaller leaflets that radiate from a common base. There are five to seven leaflets in a leaf. Each leaflet has toothed edges and a pointed tip.
Horse chestnut flowers are mainly white but have attractive pink or yellow blotches at their base. They are born in erect spikes that are sometimes called "candles" because they look as though they are lighting up the tree.
The fruits are large and prickly. They are green at first and turn yellow in the autumn. Each fruit generally contains one conker (or horse chestnut), but may occasionally contain two or even three conkers. In the autumn the fruits fall to the ground, often already open. The seeds, or conkers, are a beautiful, rich brown color and have a glossy appearance. There is a white mark at one end of each seed.
Horse chestnut trees are sometimes planted on either side of a road, forming beautiful avenues. They are valued for their beauty, the nectar that they provide for bees, and their conkers. As described below, they may have medicinal benefits as well. The wood of horse chestnut is soft, light, and weak. It isn't very good for building things.
How Did Horse Chestnut and Conkers Get Their Names?
There are several possible reasons why Aesculus hippocastanum is known as a "horse" chestnut. When a leaf drops, the scar left on the tree is shaped like a horseshoe. The scar also contains seven marks around the edge that look like the nails of a horseshoe. Another possible reason for the name is that it was once thought (mistakenly) that horse chestnuts helped cure horses of chest complaints and made their coats shiny.
The name conker may have come from the sound that's made as two conkers hit each other. Another possibility is that it was derived from the French word "cogner", which means to "hit or knock". In some regions of Britain conkers are given alternate names, including obblyonkers and cheggies. Conkers with flat sides are sometimes called cheesers.
The Conkers Game
Conkers is a traditional game in the UK, where I grew up. The goal of the game is for a person to use his or her conker to break a conker belonging to another person.
The earliest games of conkers were actually performed with hazelnuts or sea shells instead of horse chestnuts. The horse chestnut tree wasn't imported into the United Kingdom until the 1600s. The first recorded game of conkers played with horse chestnut seeds took place in 1848 on the Isle of Wight.
To prepare for a game of conkers, a player has to drill a hole through one of the seeds. A screwdriver or another device is sometimes used instead of a drill. A piece of string or a shoelace is then threaded through the hole and a knot is tied at one end so that the string can't slip out of the hole.
To play the game, one person dangles their conker and the other swings or flicks their conker at the stationary one. The players take turns swinging their conkers. A conker that breaks another one is the winner.
Competitive conkers are assigned a number. A none-er is a conker that hasn't yet broken another one while a one-er has broken one conker. However, the numbering system gets more complicated than this. A conker not only gains a point for defeating another one but also take over the points of the conker that it destroyed. For example, if a none-er breaks a two-er, the none-er becomes a three-er. It got one point for winning the game plus it gained the two points of the conker that it broke.
How to Play Conkers
The World Conker Championships
In the United Kingdom, even adults play conkers. The World Conker Championships is an annual event that is held in the middle of October. The event takes place in Northamptonshire and was started by the Ashton Conker Club.
The competition organizers provide conkers for the games and don't allow players to use their own. This rule prevents players from entering the games with an unfair advantage. There are several methods of hardening a conker, which aren't allowed in the competition. These methods include soaking the seed in vinegar or salt water and baking it in an oven. Storing a conker for a year will also harden it.
Possible Medicinal Benefits of Horse Chestnut
An extract of horse chestnut seeds or leaves may have medicinal benefits. There is scientific evidence that the extract can help chronic venous insufficiency. In this condition, a weakness in the leg veins interferes with the return of blood from the legs to the heart. The condition causes problems such as varicose veins, ankle swelling, and pain.
The NIH, or National Institutes of Health, acknowledges that horse chestnut extract has been shown to be effective for venous insufficiency. They also state that there is no evidence that it can help any other condition, however.
Any extract that's used must be free of aesculin. Aesculin (or esculin) is a toxic substance in horse chestnut. Horse chestnut also contains a substance called aescin (or escin), which is thought to produce the beneficial effects noted in experiments.
Horse chestnut extract may act as a medication, but eating conkers or leaves from a tree is dangerous. Extracts intended for medical use must be obtained from Aesculus hippocastanum and not from related plants such as Aesculus californica (California buckeye) or Aesculus glabra (Ohio buckeye). These plants haven't been tested for medicinal benefits or safety.
It's important that anyone who is considering the use of horse chestnut as a medication talks to their doctor. Natural medicines can cause side effects and can interfere with the action of pharmaceutical drugs.
Time Lapse of Horse Chestnut Trees in Different Seasons
The Leaf Miner Moth
The horse chestnut is a much loved tree in the United Kingdom. Unfortunately, in some parts of the country it's being attacked by the leaf miner moth, or Cameraria ohridella. The moth causes the leaves of horse chestnut to turn brown and fall off the tree in late summer instead of in the fall.
The damage is done by the larvae of the moth. They "mine" their way through the leaves as they feed on leaf tissue. Although infected trees don't look very attractive, they aren't killed by the moth. The damage to the leaves develops too late in the growing season to have much effect. The seeds or conkers may be smaller than normal, however.
There has been some concern that horse chestnut trees are being weakened by the moth's presence, which might make them more susceptible to microbe infections. Recent research has dispelled this notion, however.
Effects of The Leaf Miner Moth on Horse Chestnut
Bleeding Canker Disease
Scientists say that the threat of a bacterium that causes bleeding canker disease is much more serious than the threat created by the leaf miner moth. The dangerous bacterium is called Pseudomonas syringae. It creates an infection in the tree bark (a canker). The damaged area releases a sticky, reddish brown liquid. The infection may be minor. However, in severe cases the infection travels deeper into the tree trunk and kills the inner bark, the cambium (which produces new plant tissue) and the outer wood. Water and nutrient transport may be disrupted. If the infection spreads all around the tree trunk, the tree will die.
Hopefully researchers will be able to fight bleeding canker disease and prevent the infection from spreading to new trees. The loss of horse chestnut trees from Britain would be a very sad event. They have been a beautiful part of the landscape for many years.
Horse chestnut tree information from the Morton Arboretum
Why we love conkers and horse chestnut trees from BBC earth
Leaf miner moth facts from the Royal Horticultural Society
Bleeding canker disease of horse chestnuts from the BBC
More information about bleeding canker disease from the Forestry Commission
Facts about the World Conker Championships from the competition website
Horse chestnut medicinal information from the NIH (National Institutes of Health)
© 2013 Linda Crampton