Castanea sativa, the sweet chestnut, Spanish chestnut or just chestnut, is a species of tree in the family Fagaceae, native to Southern Europe and Asia Minor, and widely cultivated throughout the temperate world. A substantial, long-lived deciduous tree, it produces an edible seed, the chestnut, which has been used in cooking since ancient times.
The tree is to be distinguished from the horse chestnut Aesculus hippocastanum, to which it is only distantly related. The horse chestnut bears similar looking seeds (conkers) in a similar seed case, which are not palatable to humans.
The tree requires a mild climate and adequate moisture for good growth and a good nut harvest. Its year-growth (but not the rest of the tree) is sensitive to late spring and early autumn frosts, and is intolerant of lime. Under forest conditions, it will tolerate moderate shade well. It can live to more than 2,000 years of age in natural conditions.
The species is widely cultivated for its edible seeds (also called nuts) and for its wood.
A tree grown from seed may take 20 years or more before it bears fruits, but a grafted cultivar such as ‘Marron de Lyon’ or ‘Paragon’ may start production within five years of being planted. Both cultivars bear fruits with a single large kernel, rather than the usual two to four smaller kernels.