Horse chestnut

species of plant
The other kind of chestnut is called sweet chestnut. It is not related to this tree

A horse chestnut (Aesculus hippocastanum), also known as the horse-chestnut, buckeye, conker tree, or Spanish chestnut, is a large deciduous tree. It is native to southern Europe, in the Balkans. It is often grown in temperate climates. It can grow up to 36 metres tall. The name of the tree (and the whole genus of similar trees) is because its fruit, the conker, was used to treat horses, against cough and some parasite worms.

Aesculus hippocastanum
Horse-chestnut planted as a feature tree in a park
Scientific classification
Binomial name
Aesculus hippocastanum

Horse chestnuts are not edible for humans. The trees are not closely related to sweet chestnuts.