It is oaks such as the downy oak and above all the turkey oak that make up the deciduous forests that occupy the Quarto sector, often covering entire hillsides and preceded by pioneer thickets that tend to close the open pastures. Below the oaks there is sometimes a second tree layer, represented by smaller species such as the manna ash, the lesser maple and the field maple. In the undergrowth grow hawthorns, honeysuckles, the priest's hat with curious purple and orange fruits, wild asparagus. In areas characterized by stagnation of water there are thickets of southern ash, accompanied by the increasingly rare elm.

As for the tuffaceous valleys, they host a surprising plant community, above all for the limited extension of these environments. The reason lies in the climatic factors, in particular humidity, which condition the presence of species such as the beech normally present at much higher altitudes (over 1000 m, while here it is found at 200-300 m). The bottom of the ravines is home to hazelnut bushes and, near the waterways, black alder, black poplar, white willow. Twisted holm oaks, hackberries and figs climb the steep walls.

Large areas of the pastures are invaded by bushes, formed by rosaceae such as hawthorn, blackthorn, almond pear and various species of wild rose. Meadows and pastures, generally derived from deforestation, are rich in annual and perennial herbaceous plants, including orchids such as the rare Orchis laxiflora. Finally, also the archaeological areas of the park host peculiar plant communities with oak groves on the top of the tumulus tombs, cervine tongues in the darkest ravines,  spring flowering bulbous plants such as cyclamen and anemones, carpets of ivy.

In summary, the species recorded in the park are 947.