A châtaigne is a chestnut, as is a marron, but smaller; a marron is generally a domestically improved wild chestnut. A water chestnut is a châtaigne d'eau or châtaigne d'eau chinoise.
Northeast Corsica is known as the Castagniccia, the land of the chestnut. After the misery of the Black Death, the Genoese, the medieval rulers of Corsica, wanted the grain grown on the island for themselves but also they also wanted the island to have a reliable source of food, so offered a bounty per tree planted, and even passed a law that allowed people to own trees on other people’s land.
Other chestnut forests were planted around the island, but they took to the humid, mild schist slopes of Monte San Petrone south of Bastia like kudzu, and by the 16th century a whole chestnut civilization was in place.
Images by Achromatic, Clément Bucco-Lechat, Tschubby