Common horse chestnut

Horse chestnut trees: facts and stories

In the past, horse chestnut trees had an important role in cleaning clothes and shaving, because they contain substances called saponins, which foam up and have a cleansing effect too.

To create a kind of liquid soap, peeled horse chestnuts can be soaked in water, crushed and then boiled. This mixture can be filtered, with the foamy part then being collected and bottled. The soap will last for at least a year. How would you like to try this all-natural washing liquid? This home preparation is slowly coming back into fashion, as it’s easy to make, it’s cheap, it doesn’t pollute the environment, and it’s less harmful to your health.

Horse chestnuts aren’t just good for washing your clothes: they can help to protect them too! Placing a few of them in your draws and cupboards can prevent your clothes being eaten by moths!

Did you know?

In spring, horse chestnut trees stand out because of their flowers. The pyramid-shaped bouquets of flowers stand erect on the tree’s branches, looking like lanterns summoning pollinators.

The flowers are white with small yellow patches when they open. Insects’ vision can distinguish yellow particularly well, so this colour attracts various pollinating species, inviting them to come and feast on the nectar in the tree’s flowers. Once a flower has been pollinated (fertilised), the yellow patch on the flower turns pink! As pollinators can’t see pink as well, they continue on their way past the already-pollinated flowers and seek out the flowers that still have yellow patches.

This magic trick allows horse chestnut trees to direct pollinating insects to the flowers that still need to be fertilised. It’s not just colour that helps with this though: horse chestnut trees also use scent signals to aide this process. The yellow patches in the flowers release a scent that attract pollinators to the heart of the flower. When the flower is fertilised and the patch of colour changes to pink, the scent also changes.

Although they aren’t the only trees using methods like this, horse chestnut trees really are masters when it comes to using colour and scent to communicate with pollinating insects.

The benefits of horse chestnut trees

Horse chestnuts are the largest flowering trees. They often have a majestic appearance, and their beauty has made them very popular for planting in towns and cities. They are one of the most commonly planted species* for decoration in urban avenues, parks and playgrounds.

However, the benefits of this tree aren’t purely decorative. The extensive, very dense foliage is great at producing oxygen, and also helping to purify the air that we breathe. Horse chestnuts are one of the best trees when it comes to fighting air pollution and capturing CO2 (which is stored in their wood). The leaves filter fine particles from the air too. Lastly, the shade that these trees cast is ample and very dark, which has a cooling effect on the surrounding air. This is particularly beneficial during heatwaves!

The fruit of horse chestnut trees isn’t edible, but it has numerous uses (see above) and recognised medicinal properties. Extracts from the tree are used for treating problems with blood vessels.

How to recognise a horse chestnut tree

Leaves

large, fan-shaped, with compound composition of 5–7 mini leaflets (folioles)

Folioles

long and oval-shaped, with coarsely serrated edges

Foliage

bright, dark green in spring/summer; red in autumn; and no foliage in winter

Flowers

white with yellow and pink patches; grouped in large, erect clusters (panicles)

Fruit

burrs; round, green, spiky capsules (~6cm)

Seeds

brown to reddish brown, smooth and glossy

Bark

reddish brown, becoming blackish grey; scales that flake off in patches (desquamate)

Specifics about this tree

Throughout Ixelles’s history, Avenue Louis Lepoutre has always had a double row of horse chestnut trees planted along the whole length of the road.

They were planted when the avenue was first laid out, between 1905 and 1914. By the time the trees were around 50 years old, they had all developed large crowns. Their crowns grew larger and larger, eventually joining together to form a magnificent canopy above the avenue.

The trees transform the avenue into a shaded promenade. They have already witnessed five generations of inhabitants in the neighbourhood. Today, these horse chestnut trees serve as the neighbourhood’s air conditioner (see above). They aren’t doing too well though: drastic pruning in the mid-90s left them weakened. The milder winters in recent years have also reduced how well they can fight off certain pests.

(Story and photos created by Priscille Cazin- Sylvolutions)

This portrait is:

- Enriched with an illustration from the Belgian Federal State Collection on permanent loan to the Meise Botanical Garden.

- An initiative of Christos Doulkeridis, Mayor of Ixelles , Audrey Lhoest, portfolio holder for Environment, Green Spaces and Planting, and Tourism and the Ixelles Communal executive