The deciduous forests in the lowest reaches of the reserve are dominated by European beech (Fagus sylvatica) and European hop-hornbeam (Ostrya carpinifolia), and more rarely — sweet chestnut (Castanea sativa). The coniferous forest belt is composed of Scots pine (Pinus sylvestris), black pine (Pinus nigra), Norway spruce (Picea abies), European silver fir (Abies alba), Bulgarian fir (Abies borisii-regis), Macedonian pine (Pinus peuce) and Bosnian pine (Pinus heldreichii). The dominant tree species of lower coniferous belt between 1000 and 1450 m is the black pine, while the woods at higher altitudes up to 1800-1900 m are formed by Bosnian pine and are the largest of their kind in the Balkans. The reserve, as well as Pirin National Park are the only habitats of this pine species in Bulgaria. The average age of the Bosnian pine forests is 60 to 120 years, reaching over 200 and rarely 400 years. The height of the individual trees can surpass 30 m. The beech and the fir grow in shady habitats with riches soils while the Bosnian pine occupies zones with less nutrients.