The Castilian-Leonese slope of the Cantabrian Mountains and the northern foothills of the Sistema Ibérico have a rich vegetation. The most humid and fresh slopes are populated by large beeches, whose extension areas can reach 1,500 m altitude. In turn, the European beech forms mixed forests with the yew, the sorbus, the whitebeam, the European holly and the birch. On the sunny slopes the sessile oak, the European oak, the ash, the lime tree, the sweet chestnut, the birch and the scots pine (a typical species from the north of the Province of León).