The great variety of ecological conditions in the arreea makes it possible for a great diversity of vegetation to develop. The limestone areas up to an altitude of eight hundred metres are covered with mixed deciduous woods. Hornbeam, Neapolitan maple and ash trees grow on the colder slopes, while in the warmer, more protected areas, there are oaks, as well as shrubs such as juniper, heather and rockrose. Beech woods are to be found only at the lower reaches of the Valle Scappuccia and the Valle Acera, thanks to the unusual climatic conditions. Here, in the springtime, woodland undergrowth is filled with wild flowers, with the torquoise scilla (squill), the violet hepatica nobilis, yellow primroses and primulae. Conifer woods, such as those of Monte Predicatore, were planted in the 1930s and 1940s with non-native species such as the black pine. The vegetation on the warmer slopes of rocky cliffs is typically Mediterranean with ilex there are pistacia therebintus (turpentine tree), phillyrea, arbutus unedo (strawberry tree), smilax (sarsaparilla) and thyme.
The northern slopes, on the other land, are covered by Scutellario- Ostryentum, along with bay in the Frasassi Gorge and box in the Della Rossa Gorge. There are also some important and extremely rare species , which are found in a limited number of placet and are real botanical treasures: Moehringiapapulosa, Potentilla caulescens, Rhamnus saxatilis, Saxifraga australis and Ephedra major. Along the rivers , there are many willows and poplars as wella as white thorn, sloes, wild rose and elder. Many kinds of flowers are to be found in the meadows and numerous clearings, including anemones, mountain asphodels and narcissus tazetta. Present among the vast genus of Orchis are orchidea tridentate ( with its small, more or less spherical- shaped pink flowers which have a magnificient effect when seen together), orchidea sanbucina ( whit flowers ranging from yellow to dark red) and orchidea maggiore (with purple coluored dots on a red or white back-ground).
