Horse Chestnut  (Aesculus hippocastanum)

Native to Albania and Greece, the Horse Chestnut was introduced to Britain in 1616 and is now common in parks, village greens and city streets. It is easily recognised by its leaves, its spectacular flowers in spring and its production of ‘conkers’ in autumn. It can be confused with the Red Horse Chestnut, which has red flowers and crinkled leaves. The Horse Chestnut is not related to the Sweet Chestnut, which is in a completely different botanical family.

horse chestnut tree in May

Horse Chestnut tree in flower in early May.

horse chestnut tree compound palmate leaf

The leaf of the Horse Chestnut can have from 5 to 7 leaflets. This is a  Compound Palmate leaf. It is compound because it has more than one leaflet and palmate because the 5 leaves radiate out from a single point like the palm of a hand.

horse chestnut flower panicle

Flowers just beginning to open at the end of April. This type of flower is called a panicle by botanists. 3 to 6 individual flowers are located on each branch of the ‘panicle’ with the branches being longer at the bottom than the top, giving a cone shape. Flowers at the top are male, those at the bottom female and those in the middle combined male and female. Flowers are pollinated by bees.

horse chestnut fruits

Flowers lose their petals and the female or mixed flowers that have been fertilised develop into fruits by late June.

horse chestnut conker

The ovary develops so that the seed is surrounded by a green spiky ‘husk’ by the end of August and the ‘husk’ splits ready for the seed – known as a ‘conker’ – to fall to the ground in September. This type of fruit is called a capsule.

horse chestnut bark

Close-up of the scaly bark on an old tree.