One of the most prominent features of the Sierra de Guara vegetation is its contrast between the northern and southern slopes of the valley. Due to their orientation and the geomorphology, we encounter a great variety of species. 

The Sierra y Cañones de Guara Natural Park is a transition zone between the Pyrenees and the Ebro Basin, and is host to diverse ecosystems of Pyrenean and Mediterranean species.

The gall-oak grove dominates the rural skyline, followed in height by the European red pine and beech trees. At higher altitudes the black pine can be found, accompanied by spruce trees. 

The holm oak is the most important tree in the Mediterranean forests, along with the pine at higher altitudes. On the Sierra’s slopes, more prominent scrub stands out: boxwood, Echinospartum horridum, and, to a lesser extent, kermes oaks. The herbaceous species become characteristic of the vegetation at the summit. At the bottom of the valley, Kermes oak bushes can be found, and the areas with the greatest slopes contain rosemary, boxwood, and gorse, and the notable presence of dry meadows.

On the banks of the cooler and more sheltered ravines, the holm oak groves are accompanied by a shrub layer formed by Arbutus, Laburnum trees, Laurustinus, mastic trees, greenbriers, oleander, and even holly.

The vegetation in rocky areas is most clearly found in the crags of the ravines that are populated by very specialized plants, such as Petrocoptis guarensis, Valeriana longiflora, Saxifraga longifolia, primroses, and the long-leaved butterwort. As altitude increases, the boxwood dominates and the Kermes oak retires to dry and sunny areas of gravel.

Moreover, there are also cultivated fields where the traditional species grown in this area can be found. Here, there are olive trees, almond trees, cereal plantations, walnut trees, and more.