Aesculus hippocastanum, the horse chestnut, is a species of flowering plant in the maple, soapberry and lychee family Sapindaceae. It is a large, deciduous, synoecious (hermaphroditic-flowered) tree. It is also called horse-chestnut, European horsechestnut, buckeye, and conker tree. It is not to be confused with the Spanish chestnut, Castanea sativa, which is a tree in another family, Fagaceae. Description Aesculus hippocastanum is a large tree, growing to about tall with a domed crown of stout branches. On old trees, the outer branches are often pendulous with curled-up tips. The leaves are opposite and palmately compound, with 5–7 leaflets long, making the whole leaf up to across, with a petiole. The leaf scars left on twigs after the leaves have fallen have a distinctive horseshoe shape, complete with seven "nails". The flowers are usually white with a yellow to pink blotch at the base of the petals; they are produced in spring in erect panicles tall with about 20–50 flowers on each panicle. Its pollens are not poisonous for honey bees. Usually only 1–5 fruits develop on each panicle. The shell is a green, spiky capsule containing one (rarely two or three) nut-like seeds called conkers or horse-chestnuts. Each conker is in diameter, glossy nut-brown with a whitish scar at the base. Etymology The common name horse chestnut originates from the similarity of the leaves and fruits to sweet chestnuts, Castanea sativa (a tree in a different family, the Fagaceae), together with the alleged observation that the fruit or seeds could help panting or coughing horses. Although it is sometimes known as buckeye, for the resemblance of the seed to a deer's eye, the term buckeye is more commonly used for New World members of the genus Aesculus. Distribution and habitat Aesculus hippocastanum is native to a small area in the Pindus Mountains mixed forests and Balkan mixed forests of South East Europe. and endemic to the Balkans. However, it can be found in many parts of Europe as far north as Harstad north of the Arctic Circle in Norway, and Gästrikland in Sweden, as well as in many parks and cities in the northern United States and Canada. The compact native population of horse chestnut in Bulgaria is distinct from the horse chestnut forests of northern Greece, western North Macedonia and Albania. It is limited to an area of 9 ha in the Preslav Mountain north of the Balkan Mountains,