The name Castanea is probably derived from the old name for the sweet chestnut, either in Latin or in Ancient Greek.
Another possible source of the name is the town of Kastania in Thessaly, Greece; more probable, though, is that the town took its name from the most common tree growing around it. In the Mediterranean climate zone, chestnut trees are rarer in Greece because the chalky soil is not conducive to the tree's growth. Kastania is located on one of the relatively few sedimentary or siliceous outcrops.
They grow so abundantly there, their presence would have determined the place's name. Still others take the name as coming from the Greek name of Sardis glans (Sardis acorn) – Sardis being the capital of Lydia, Asia Minor, from where the fruit had spread.