Forest vegetation occupies about 25% of the entire surface of the Polvese Island and extends mainly to the north. The forest, for about 11 hectares, is almost entirely made up of an almost pure holm oak of considerable naturalistic interest: it is the holm oak wood of San Leonardo, so called for the homonymous church that was once present in this area. It is one of the few high-trunk holm oaks in Umbria: the average height of the trees is about 15 meters.
Inside the wood there are also some centuries-old specimens of downy oak.