Known for their large size and showy insect pollinated flowers, the horse chestnuts or buckeyes (as they are known in America) are popular ornamental trees.
Both common names come from their brown nuts; buckeye derives from the resemblance to a deer's eye and horse chestnut may derive from the fact that the nuts contain the chemical aescin, historically used to treat inflammation in horses.
Alternatively, some think that the prefix 'horse' meaning hot, fierce, or pungent is a reference to the unpalatable nature of the nuts.
Common horse chestnut, Aesculus hippocastanum
The most familiar member of the genus, the common horse chestnut was introduced to Britain in the 17th Century from the Balkans in southeast Europe as an ornamental. Today it is widely cultivated in many parts of the world.
It is most attractive in May when covered with white flowers which are held in erect clusters rather like candles in a candelabrum. Look closely and you will see that each individual flower has yellow blotches, which later turn red to signal to bees that the flower has been pollinated. However, for children, September and October are undoubtedly the best months for conkers. Found throughout the arboretum, several specimens stand just outside the Great Oak Hall.
Red horse chestnut, Aesculus x carnea
This red-flowered hybrid is a cross between our common horse chestnut and the red buckeye Aesculus pavia from the southern United States. It has been in cultivation since the 1820s, often grown in avenues and parks where its large shapely stature can be well appreciated. It is often seen as the smaller, deep pink-flowered cultivar known as ‘Briottii’.
Indian horse chestnut, Aesculus indica
Westonbirt Arboretum is fortunate to have a number of fine (including the UK champion) Indian horse chestnuts. As its name suggests, the species is native to the north west Himalaya from where it was introduced around 1851. Although it does not get quite as large as our common horse chestnut, it is a more handsome plant. The leaves themselves are narrower and shapely and the flowers, when they appear in June or July, are more delicate and have a tinge of pink. As an added bonus the autumn colour can be quite good and the dark (almost black) fruits appear in November.
Sunrise horse chestnut, Aesculus x neglecta 'Erythroblastos'
This is a spectacular small tree, best known for its brilliant shrimp-pink new leaves in May/June changing to pale yellow green later in the season. We have several specimens including the one pictured here on Mitchell Drive.
Japanese horse chestnut, Aesculus turbinata
Similar in most respects to the common horse chestnut, this Japanese species has yellowish white flowers in May/June. Its fruit are slightly pear-shaped and lack spines.
Californian buckeye, Aesculus californica
This is a relatively small spreading tree with leaves around 8 inches long and across. The pink-tinged flowers are fragrant and appear in late June. It also produces one of the largest fruits amongst the horse chestnuts.
Find these species and their specific locations using the Westonbirt Interactive Map.