The Pyrenean oak is a deciduous tree rarely found in Andalusia and classified as a vulnerable species in the Andalusian Catalogue of Threatened Wildlife. It grows in very restricted areas at altitudes of 600 to 2000 m with high rainfall or special microclimatic conditions and deep acid and decalcified soils, rich in organic matter, only being found in the Sierra Morena in the province of Seville. Within the Natural Park it occupies an area of 375 ha between Constantina and San Nicolás del Puerto. The most characteristic features of this tree are its deeply lobed leaves and its ability to reproduce by regrowth from surface roots.
In the heart of the Sierra Norte Natural Park, we find the Pyrenean oak groves of Cerro Negrillo and the Cañada Real del Robledo.
At 900 m, Cerro Negrillo is one of the highest peaks in the Seville’s Sierra Morena. Located to the north of the municipality of Constantina and to the south of Cerro del Hierro, Cerro Negrillo has a special microclimate, being one of the zones with the highest precipitation in the Sierra Norte, along with the Pimpollar and Padrona mountains of El Real de la Jara. The Pyrenean oak grove of Cerro Negrillo is made up of young but large oaks, interspersed with specimens of cork oak, holm oak, Portuguese oak and dense scrub. It is also worth mentioning the presence of the only endemic plant species of this Natural Park: Gyrocarium oppositifolium, a plant of the boraginaceae family that grows on grasslands and in clearings of thickets and forests, on granite soils. Due to its height and location, the hill is of great scenic interest and has a panoramic viewpoint.
The Pyrenean oak grove of Cañada Real del Robledo is a mass of Pyrenean oaks, with specimens of up to 21 m in height, bordering a 600 m section of the cattle track. Next to them, we also find some specimens of Portuguese oak, and thicket consisting mainly of gum rockrose and bramble.