

Common name: Horse Chestnut
Scientific name: Aesculus hippocastanum
Horse Chestnut is a large deciduous tree that can reach heights of between 30 – 40m and can have a branch spread almost as wide. Horse Chestnut trees can live for up to 300 years.
Identification
Leaves: Horse Chestnut leaves are palmate, comprising of 5-7 leaflets spreading from a central stem. Leaflets are pointed with a serrated edge.
Buds: The large leaf and flower buds of Horse Chestnut are protected by a dark red, sticky coating, which melts with the beginning of warm weather to reveal flowers and leaves that quickly appear. These buds are clearly visible, even from a distance and during winter months.
Bark: Horse chestnut bark is smooth when young and pinky-grey in colour. With age, this smooth bark becomes a darker greyish-green colour and develops thick, scaly plates.
Form: Large, dome-shaped crown with widely spreading lateral branches.
Reproduction
Monoecious. Flowering occurs at the start of April. Individual flowers have 4-5 fringed petals. Petals are white with a large blotch at the base that is a bright purple/red or yellow. Once pollination occurs, flowers develop into glossy red-brown conkers, encased inside a green husk, armed with sharp flexible spines to protect the fruit inside. Fruits are ready to fall in September, hitting the ground and splitting the outer casing, containing either one large flattened conker, or 2-3 smaller, flat sided conkers.
Growth habit
Horse Chestnut trees grow very rapidly. Growth in young trees may be between 60-80cm from mid-April to late July. Growth rates slow with age and many trees at around 150 years old shed branches and begin to break up.
Origin
Now common in the UK, the Horse Chestnut originated in the Balkans in South Eastern Europe and was first introduced into the UK as an ornamental tree in the late 16th century.
Interesting fact
The horseshoe markings found on the twigs of Horse Chestnuts trees are the scars from where leaves have fallen off. The association with horses is thought to be the origin of the trees name.
Ecological importance
Horse Chestnut flowers are used widely by insects, as they provide a rich source of nectar and pollen. The leaf of Horse Chestnut is fed on by various moth larvae, including that of the Horse Chestnut Leaf Minor. The caterpillars also provide food for other animals such as birds. The conkers are also food for deer and other mammals.
Associated Pests and Disorders
The Horse Chestnut Leaf-Miner
A moth whose caterpillars feed on the inside of Horse Chestnut leaves. This leaves brown blotches that show the path of the caterpillar or ‘mines’ between the veins of the leaf. Leaf miners can cause the tree to appear as though it is in its autumnal phase and can also cause the tree to lose its leaves early.
Honey Fungus (Armillaria)
Honey Fungus is a Parasitic fungus in the Basidiomycetes family. It spreads through the roots and feeds on the live wood of the tree. Armillaria is a facultative saprophyte, it can also feed on dead plant material which allows it to find a host, kill it, and extract all the nutrients from the dying and dead tree before it moves on to the next. Honey fungus is considered a destructive forest pathogen. It is very long-lived and can form some of the largest living organisms in the world.
Other associated pests and disorders include Ganoderma, Phytophthora, Horse Chestnut Bleeding Canker and Guignardia leaf blotch.
Properties of Horse Chestnut and uses
Appearance/colour: Heartwood is a creamy white colour or yellowish brown and is not clearly distinguished from the white sapwood. Horse Chestnut has a fine texture with a wavy grain.
Uses: Commonly used for wood turning, plywood and furniture.
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